Lucie Hmmmmm...
OK, I see the problem now. Unfortunately, this one is probably a "can't fix".
https://imgur.com/a/6Db36QO
What's happened here is that the graphic you've pointed out is the product of two different fence tilesets on the "B" or upper layer of the tileset used to generate the Gawnfall map. If you look at the image I've linked above, you can see that the right half of fence area you've pointed out is generated from the tiles on the lower center left of the image. The leftmost tiles of the area are drawn from the second fence immediately to its right. They're spliced together and they don't quite match up.
We'd have to get someone who's a graphics editor to go in and modify the tileset file to nudge the center fence up a few pixels so that it's flush with the other one. It has been done before, Esthera's sprite was a few pixels above the level of most of the character sprites so she wasn't flush with Simon when the PC talked to her from the side. I think it was Lamsey who fixed it. But we can't mod the flowers without breaking the appearance of the fence area on the right where the full flower patch is used.
This is really just one of the limitations of RPG Maker VX Ace, and I think we have to live with this one.