ForceofNature 1) She never joins the harem, because she is killed/ married off/ turns out to be evil/ loses faith in Simon
2) She has/ she will attain proficiency in the Tower, and could even up as a goddess, to make her fit into the "other" category.
There's an option 3) for Elleani. There used to be an additional slot for non-combat people that was removed, and another slot was added to leaders. Fulminato is the master of previous game code builds, but I think that leaders slot has since been removed. So it's possible that Elleani was originally going to be a non-combat research historian, but SL decided that she was really more of a New Givini leader than a non-combat. What happened from there is that either there was a code update for the leaders harem when Esthera, Neranda or Fheliel were added that deleted the extra leaders slot unintentionally, OR that she thought better of the reclassification and moved Elleani back to non-combat but forgot to add the non-combat slot back.
SL is basically constantly juggling 12 balls with TLS, so it's natural that one will get dropped from time to time.
I'd suggest that the Vunne variable probably isn't RP, and that if Mestan gets a slot, it'll be because he turns the tables on Lilith and ends up "hollowing her out and wearing her like a suit".