When crawling forward the animation looks great, but when crawling backwards it plays the same animation and it doesn't make sence. Demonstration: https://www.youtube.com/watch?v=cCmJ1e7BHLQ
My suggestion is simply reversing the animation when backwards key is pressed. So it will look like the player is pushing with their hands instead of pulling.

Hm, that is actually a good point and question. Currently it uses the same animation progress like the vanilla "crawling"(swimming) animations, which is missing this backwards logic. Will have to look into how to handle this.