I just released [Animancer v3.1]( Animancer - Less Animator Controller, More Animator Control page-3#post-4851260) which includes the new example that remakes the player from the 3D Game Kit to use Animancer instead. In particular, this section goes over the locomotion problem I mentioned.
It turns out that I was wrong about being unable to jump during the landing animation. The actual issue was an even simpler mistake on their part: the PlayerController only checks the jump input in FixedUpdate so it can randomly miss the input if there happen to be multiple Updates between two FixedUpdates.
Also, I was never able to get the character to levitate by jumping and getting hit at the same time like you described, but again I think that was actually a simpler issue … it just does it randomly for no apparent reason as you can see in the first gif here.