Title says it all. Capes decoded from unascribed/Ears capable skins are not affected by Wavey Capes. Easy way out is to call it quits and mark it as incompatible, because as far as I understand from it, it uses its own feature renderer that then calls a delegate. It's a multi-version multi-loader thing of beauty.

Wait, why does that mod even do anything with Capes?!?

There may or may not be a hidden feature that may or may not add capes.

Here's a test skin (my own) or if you'd want to spawn a bot, then my ign is hibiscvs, I won't be changing my skin for a very long time.