One of my favorite things about this game and those like it is seeing the changes in the girls over time. One thing that I felt was missing was a proper gallery. I know there is a gallery that exists in the current version, but it didn't really capture what I would want in a gallery: The ability to compare the different stages in the bimbofication process, like you did in Butterfly Therapy. In other games, I would also want a way to re-view the scenes of the transformations taking place, but in this game that isn't such a big deal in my opinion.
Another thing I really liked about the game was the beginning part with Madeline, since the transformation there was less linear and had more stages to it. Even if it's only for a few girls out of the many, I'd like to see some more areas like the first town with one "central" girl that takes a while to bimbofy with more stages and possibly nonlinear things (like breast expansions, lip expansions, and clothes/hair being separate paths to go down whenever needed). Maybe even with several adjacent girls that might take less time to bimbofy/have less stages, but give, as a reward, bimbofication for the "central" girl.
Also, one thing that kinda bugged me, mostly in the girls by Olena Minko, was that you could sometimes predict how the girls would transform. Like, it would usually be three stages, first being "lose some clothes" then "big lips" then "bigger boobs". This isn't really present for the more recent stuff, especially the Backroom characters, but I figure I'd mention just in case. Also another thing for the Olena Minko girls that is probably just personal preference, a lot of the edits you did of their work had lips that looked rather unappealing to me, specifically due to their positioning. Like, it looked like the mouth had moved down on the face. You can see what I'm talking about the most on, for example, Elsa, Raya and Raven.