This is likely to be out of scope. character_anim tries to be as game-agnostic as possible by only expecting a few standard bones the Minetest Game default player model (character.b3d) typically provides: Body, head and right arm. I don't plan to add custom models. I could add support for more advanced model conventions, but that would complicate the code and probably only serve a single game (Mineclone) which provides such a model (and already has its own provisions for animations).
You mean that if I play Mineclone I can already see character's animations as I'd like provided by default? Then can I take only the complex animations files from it and release them as mod if I'm able to do it? Just to bring them on my worlds outside Mineclone 😄.