In 1.10+, Husks should replace Zombies in Desert Environments and Strays should replace Skeletons in Snow environments.

This does not happen with Zombie Awareness.

How have I not seen a stray before, even regularly spawned before... I see strays in the code though, I should adjust my mob duplication and fresh spawning code to account for this yeah.

Forgot to close this, a new generic system was put in place that should have those covered now, and if not, you can config it to be used for them. Feel free to open a new issue for mobs if you run into problems.