Okay, new plan now that I’m better: First, I’ll work to get the stable release and demo ready and published. (This will catch up documentation with Modifiers, including ones that are animated even while fully applied like this.)
Afterwards, I’ll implement the in-Window sprites and (separately) hopefully also another small feature I had in mind. Note that in-Window Character sprites will most likely not be affected by the new Modifiers, but layer rules will work as normal.