What movements do you not like? Is it rotation the wrong way around? Unfortunately this is difficult to fix.
When mixing between two world rotations (the two poses from your two animations), there are 2 directions around the circle to compute say halfway between the rotations. AnimationState chooses the shortest direction when the mixing begins.
The animations are moving, so to prevent jumping to the other side if the other way around becomes the shorter way around during the mix, AnimationState sticks with its initial decision throughout the mix. It can be reset with TrackEntry resetRotationDirections. See the description there.
There is also TrackEntry shortestRotation. This causes AnimationState to always use the shortest rotation direction, rather than sticking with its initial choice. This can cause world rotation mixing to jump from one side to another.
One way to handle this to apply an intermediary animation to ensure your bones rotate the way you want. For example, the animation would move to a pose roughly halfway between the two animation poses. You could check if an animation is in a state where mixing to another animation would cause the problem and only use the intermediary animation in that case.
Another way to handle this is to not use mixing between the problematic animations.
