I posted this in the Help forum earlier, but I figured I'd get a response quicker if I posted here.
I made a stage using this guide, and when I tested it, the wall collisions worked fine, but all of the textures don't appear at all - i. e. you only see black except for the characters and a few glitchy spots.
I'm not really sure what I did wrong (There's only one animation in each ModelData, and the textures are in CMPR format)
but you can download the stage here if you want to look at it.