Thank you for your detailed review! Although you could have left it in Spanish since I'm from Spain XDD
About the art, we did our best to have the most unified style possible, but take into account that there were five artists plus the ones for the chibi scenes, and even within each artist, some variations are bound to happen since they work in different projects at the same time.
I'm working on the bugs fixes right now, and about the difficulty level to get some of the achievements... Well, that's why I made a guide, so you could choose what days to spend with your love interest and what days to spend raising stats.
All in all, I'm glad you had an entertaining time with the game and that you enjoyed the plot and the characters!