I can't unlock Maria's final scene. I tried following the book's hint but no matter how many times I talk to her in her room it doesn't give new dialogue. Did I do something wrong?
There's a bug in this version of the game. If you've given her a transformative potion, it locks off the non-transformed version of the scene by accident. It's pretty much the same scene as the transformed version.
If you want it for completion's sake, talk to Rei (the fairy) and turn on the "disable content" filter for that transformation. You can get the scene, then re-enable to the content to get back to where you were.