First off, I am using this model/rig from Blendswap:
https://blendswap.com/blend/28627
It has a dozen animations. When I export to Godot (using the Blender to Godot *.escn), the only animation that actually exports is horse.rigAction (which is horse.walk). But it works (almost) perfectly and looks amazing.
But when I change the animation (such as to horse.trot) and export it, the legs distort and it runs like a drunk. And I get a fantastic list of errors.
I have tried exporting as other formats (gltb, ftx, dae, etc.), all with varying degrees of eldritch deformation. This makes me think that it might be a Blender issue not a Godot issue necessarily, but I want to see if there is anything I can do because this is exactly what I need and I will never be this good at animation.