By unrealistically, I mean they either move too quickly, or too slowly.

Issue wasn't fixed

Can you specify which animations are still having issues in the latest (1.7.0) version?

Walking animation. Player's legs moves much slower when the player is smaller and moves faster when the player is bigger. It looks weird when you goes through the portal from Immersive Portals mod and you suddenly begins moving slower.

I made a video showing it https://youtu.be/8dZ_nh8a5fk

The video appears to currently be private. Maybe you could make it unlisted instead?
If you prefer, it is possible to directly upload a video file to a comment.

I've been doing some testing, but so far I am unable to reproduce the leg movement issue with Pehkui-1.7.0+20w51a.jar and immersive-portals-0.55-mc1.16.4-fabric.jar on 1.16.4.

Oops, sorry. I opened it.

Unable to reproduce with Pehkui-1.7.0+20w51a.jar and immersive-portals-0.55-mc1.16.4-fabric.jar on 1.16.4.

Oh, sorry, I am really dumb. I installed the new version but didn't put it in the mods folder. Issue can be closed.