Thank you for the tool. I'm a programmer that had played with those files before, I discovered they come from the game ez2dj and also are used in djmax , and the RO online documentation helped me to have some fun with it.
There are many features like auto texture increment modes, that RO files don't use, but are available features that I think RO supports by default. The layer #0 , is used when you need a basic untextured color bg, maybe it's always transparent on RO but it may not
There are extra uv parameters linked to the image files.
There is also a bezier function, but the parameters were added in the RO .EZV json-like file and then converted into individual keyframes in the ezv to str conversion. That's why some animations are smooth and seem to be interpolated, but actually are made from a lot of keyframes and no morph/delta-frames, so it would be interesting, but ambitious to make the app work based on ezv/json
I also have a modified version of one of the rhythm games where I can just open it and immediately play an str natively, for testing
Here is my fork of a previous str viewer, with useful info and commits Info on animation types (I could test the missing types later to incorporate them)
Cheers