This has been a long-time missing feature, capes wont render on latex humans either (originally noticed by Yird)

I don't think it would be too hard to add this onto the humanoid like latex creatures, however...
Centaur, Dark Latex Pup, etc, would be more complex.

I remember why I didn't originally add the cape layer. It was because the cape model is baked into the default player model, whereas the beasts didn't have one in their model. I can fix this by creating a cape model, and have it align with the entity's torso.

In addition, it would be the same for the centaur as it is for the other entities. And I'll just not give the pup a cape.

After testing, the centaur's lower torso clips with the cape badly. Perhaps I could make a shorter cape model.