So I saw this movie a few weeks ago and really liked it. The visuals were incredible, the music was amazing and the story really strong. I really liked how it explored family dynamics and how expectations can effect the whole family and how perspectives can differ within the family. I've been listening to the music a lot in the past weeks both the english and spanish versions. My biggest complaint is that it probably would have been better as a series, seeing we don't get as much time with all the family members as I wanted. I really liked Tia Pepa's side of the family but they're not focused upon as much as Julietta's kids.
As for a KH level I think Casita could easily be the whole world, but ideally we'd also get some of the town.
I can easily see all the rooms making for a very interesting and diverse world. We'd have rocky terrain with Luisa's room, Floral fields in Isabella's room, rainforest in Antonio's room and Bruno's room would be a dessert, this would really make for an interesting setting and we still have rooms that we don't know what they'd be like.
I'd prefer for the visit to take place after the movie seeing I don't see how SDG really could fit into the family drama of the Madrigals. I wouldn't mind Mirabell being one of the New Lights, she'd also make for a fun companion. However part of me would prefer her sisters as party members seeing their powers are the most RPG suited, maybe there's something threatening her and her sisters join Sora to save her.