Another thing I've had to get working for caves out of necessity, that will affect other tilesets. Since caves are being generated with walls that have waterfalls, and I'm also re-generating and shifting around all the existing palettes, I've had to figure out how the game flags a particular palette to cycle through its colors. The game uses this for most water animations, and other things like those rainbow trees in Ice Country.
Now that I set this up for every set of palettes that I generate, not only should the cave waterfalls "flow" correctly, but the island tileset water should also move around appropriately now. It's mostly irrelevant for forests (only affects the waterfall tile I mark the exit with) and entirely irrelevant for ruins .. I think. Actually, the fireplace tiles might use it, so maybe I'll check that out too.
I'd post an example but I'm way too lazy to take a video capture of it and turn it into a GIF. You'll see it when v0.50 comes out or when I do a test stream.
As for caves for v0.50, they're still a little glitchy, but they're coming along.