I consider this work pretty much complete.
![IPB Image](https://i.imgur.com/1hMoEr7.gif)
There are three remaining issues:
1. Transparency. It is
currently bothersome to get these Python image libraries to make animated GIFs with transparency.
2. Image x,y offsets. The offset interpretation of the data was correct, but the sprites can be offset beyond the bounds of the canvas. I can correct for this by detecting how far they're off-bound and offsetting the entire image, but you'd lose information about the original.
3. Palette swapping. There's no palette-swap info in these files.
These can all be taken care of in-bulk using an image processing program like ImageMagick.
The loop index interpretation seems to be right, but I know of no way to represent that in an image file.