TLDR:http://s000.tinyupload.com/index.php?file_id=53685325855447664542 This gets Ginasta's RP to 43 by the end of the current build, has way more ProN than the save you posted, and only loses a Trin max copy. Compared to my original save, it doesn't lose that much ProN in order to gain 2 more ginasta RP and some higher hidden scores, but it does lose a good amount so I still think my original save is more optimal, but you might find this one more to your tastes.(If you dominate varia and fuck altina immediately you can skip the dusty horde investment, not piss off the little girl, and get Ginasta to 46 and max copies trin 10 by speaking to her first after the reunion. If you allow varia's rape and fuck altina immediately you can get Trin max to 11 while still having reshaped varia for max vhala score. Both routes seem more optimal than saner altina unraped reshaped varia which was the baseline we're using, but I still worry about the second of those routes pissing off the little girl)
First off, I consider cache excavation mandatory for an optimal playthrough because it's a permanent character upgrade, no matter how trivial. Nothing is as important as that is. A few other frameworks I use for optimization are If a check needs 20 religion or 40 social there's no point in having 21 religion or 41 social. So if there is no check that needs a hidden score to be higher, the hidden score gained by an action is worthless(But obviously take the action that gives you better hidden scores if they both have the same cost). Non hidden scores like ProN are more valuable than hidden scores, so getting the most ProN in the end is a primary optimization goal just below character upgrades like the incubus king cache as long as you aren't failing checks. And finally, we've already seen all of the effects of the battle of yhilin fallout. After weighing the decision for a long time, I concluded deliberately sacrificing the chaos score in that battle is probably worth it for the ProN it saves you in the end, but I didn't realize it was costing me ginasta rp at the time so I'm less certain about that now.
Aramite supplier isn't a huge return on investment, but it's immensely profitable compared to almost anything else you could spend those funds on. By the end of the third arclent war it's already earned 10k in profit. It's useless for the third arclent war though for sure, since you want to just barely get to the point you can control supply lines on the aram front in order to get aram collateral damage above 20 at the same time. The extra 10k cost on yhilin supplier does pretty much negate that gain though until the first round of chapter 5(not a loss though), but you can't ever buy the aram supplier if you don't buy it there too. Not having Aramite Supplier is a bigger loss to your final score than the yhilin score and yhilin acceptance from having high chaos in the battle of yhilin.
Speaking of which, first off, if you're talking about my all 3 banks optimal route, you can just guard ari yhilina instead of intercept ari-khan if you want to buy the dusty horde to get chaos down to 4 or less so essence shielding is almost useless there(Well not entirely true, it can save you 10% discretionary funding by lowering chaos to 3 so you can clear it for free I suppose) and only having 11 quality and 29 size is a loss there(4 army size and 1 collateral damage, and the 4 army size is worth like 20% funding). In order to maximize ProN while getting the best result for the third arclent war you have room to spare if you do poorly in the battle of yhilin too. You gain just as much ProN whether chaos was high or low(and 7 chaos is the same as 5 chaos in the end, so you can further optimize the battle by making it even higher once you accept it doesn't need to be 4 or less), and you'll never get more than 10k pron from the discretionary funding not having dusty horde costs you(40% discretionary funding is worth at most 10k ProN and it's often only costing you 30% funding).
RP for girls from deeds of Vinario is worthless unless it helps pass a check. The Takkan score is also worthless since Takkan score is way way higher than it needs to be, and no arclent acceptance check it could help with needs the bonus so far either. I'd rather have 100000 ProN I just never spend than buy the deeds, and you can invest that 100k in earning more profits. Why give that little shit any money at all when you can just say "Takkan is mine and your paper is worthless" and let him tantrum knowing he won't achieve anything.
Yhilin bank is never worth buying round 1 of chapter 4. It's only a 1/3 return on investment per iteration at that point. Downgrading from the bank to the crystal refinery costs you at minimum 1 profitable investment purchased immediately after the third arclent war too(Although you can buy that investment later) but missing the profits from that investment snowballs to more than 200k pron in losses in the end so the discount on buying the refinery never materializes either. There's always something better to buy unless you're willing to fail the 40 social check(and lose the Elleani RP, which matters come gawnfall) in the succession crises. My latest calculator save I just uploaded in my previous post doesn't buy the bank before the war though, but it needs both the crystal refinery AND the mercenary fleet to catch up to the losses from not buying the bank(The mercenary fleet is nearly a scam true, but you still want to buy it eventually just for high score sake and it costs much less now than later). You also wouldn't want to buy crystal refinery before investment round 3 of chapter 4 anyway if you didn't buy it at ardford, it's just not profitable enough compared to everything else you have to choose from after making necessary purchases to pass checks, so having to wait until ardford reopens doesn't cost you anything as far as that's concerned. This save also can't afford to buy the aram eustrin embassy until round 3 instead of round 2(But it has actual profitable investments to spend that 200k on that the other saves have pretty much run out of by that point).
As for choosing the north in the negotations. If I choose the north instead of spending 10% discretionary funds for an extra noble campaign I gain an extra 5k ProN to my score which is worth more than 1 extra yhilin acceptance. Even if I didn't need the extra VP, I'd almost always choose the south instead which still costs 1 yhilin acceptance unless the loss of 1 yhilin acceptance would cost me an arclent acceptance by dropping it just below a multiple of 4 before third arclent war. Yhilin economy is worth more than yhilin acceptance, and you have yhilin acceptance to spare. The loss of 2 army size there from holding ground instead of retreating costs you 4 army size after the third arclent war which is almost always enough to drop it below 175 army size or force you to spend more discretionary funding boosting army size, and army size there matters to earn the +5 army size for 175 or more army size remaining when it's time for the thenoursian war(Granted the single point of Erosian front that can help you earn is pretty much worthless, but I don't like failing checks related to army size if I think there's any chance the army size variable might come up again).
I could have sworn Maxing Janine RP before her chat with Ginasta is impossible unless you did things differently round 1. checksHmm what do you know, I actually still place some value on Ginasta rp since we haven't maxed that yet. Still cost you ProN but worth considering for the 3 banks route. 2 Ginasta rp is not worth losing the incubus king cache though, wonder if you could get it by sacrificing the unmen petition in ardford to buy dusty horde. That's giving up vhala rp for ginasta rp though and vhala rp is rarer. Something to toy with if we need even more Ginasta RP in the end, but I'll concede you might have a point about this at least.
Most of your suggested changes aren't really optimal, giving up ProN for useless hidden scores way in excess of any checks the game throws at you, but the extra ginasta RP might come up so I've switched my save to a not completely ditching the battle of yhilin to max janine before the conversation with ginasta. You still can't convince me that buying the deeds of vinario is an optimal investment though. If I want the Trin RP I'll just change the way I deal with Altina and/or Varia(I Kind of prefer less sane altina and Dominated Varia in my playthroughs anyway, but we've been operating on a complete opposite of that baseline as that was the request that spawned this discussion), and every other RP it gives is useless(no point getting megail to 100 at battle of yhilin, but it is useful if you want to do that for some crazy reason).
Lets look at your playthrough you posted in the thread and compare it to mine. You don't get the incubus king cache, you only have 165 army size in the thenoursian war(probably ok actually, but I set 175 as the goal because that's what the check calls for) and hmm you stopped partway through the final investment phase of chapter 4 so let's use that as the end point.
At that point in your save you have: 4124500 ProN available and have 6225000 in investments I haven't purchased yet in my three banks save. My 3 banks save has 5168500 ProN available and has 6909000 in investments your save doesn't have yet. Your save is 1728000, almost 2 million, ProN behind my three banks save. Other than the battle of Yhilin and 1 more max Trin copy, your save doesn't pass any checks that my save doesn't(Although both saves only need 7 trin copies, you just chose to copy the aramite priestess even though it's not needed since it does give some okay scores).
Ignoring bonuses for investments just not bought yet and differences in torturing Estavan, You have... a maxed out lynine and 5 more fheliel rp, I have 3 more Ginasta rp, and 5 more neranda rp. I have more yhilin acceptance, you have quite a bit more Arclent Acceptance(9 higher than mine at the end of the third arclent war, kind of excessive really since even I only need 1 of war monument or succubus band tour to get 50+ Acceptance by gawnfall and the band tour is quite profitable if you don't buy the war monument in order to get +1 social and new givini score to 40 before round 2 and I use it to get takkan score to 40 round 2 as well).
In any event, other than arclent acceptance, which my save still has more than enough of so far, my 3 banks save blows yours out of the water as far as any of the criteria I use to measure success goes by(With me actually having the incubus king's cache more than making up for that hidden score imo). It might be worth me tweaking my save ever so slightly to get +5 ginasta over your save though, didn't realize it was so easy to get janine to 100 before her conversation with ginasta.