Very nice studies, I love your character constructions, and I mean I LOVE them, I can't really help you with the far right post though, It looks fine to me, but as I am a total newbie to art in general you can't really trust those words xd.
Though I did notice some things that were off in your perspective study, the first thing that stuck out to me were the windows, one looked like it was further up than the other, so I downloaded the image and popped it in to photoshop and I found some mistakes, not so much one window being higher up than the other, rather the bottom part of the windows were off.
Don't mind the quality, I opened the image in a way too big canvas so It got kind of screwed xd.
The mistakes I found are shown with the red lines, Main issues I've found is some lines aren't parallel to the Horizon Line, and some vertical lines aren't straight, which causes a slight skewed look to objects and such.
Could be my photoshop acting up and it's perfectly straight, but just smt to look our for.