The cow model is, uhh... yeah.

I am using the Custom Entity Models mod, though I have yet to try it with Optifine/Optifabric. Will update when tested.

UPDATE: They appear to be normal with Optifine. It seems like an issue with the Custom Entity Models mod

I removed the CEM mod and it worked fine, it's just now that Zombie Villagers are broken whenever the packs are layered properly.

Can confirm, zombie villagers are buggy

I removed the CEM mod and it worked fine, it's just now that Zombie Villagers are broken whenever the packs are layered properly.

This is now fixed, download the master from GitHub or you can wait for the next update! (Sorry for the wait!)