I just updated to latest UFE 2 from asset store, and see that you've added a better allow airborne side switch behavior for the 3d fighter, great!. but then I see this jerky camera behavior. I started debugging this and found that jumping from left side to right side, this code fixes it:
CODE REMOVED BECAUSE IT WAS WRONG APPROACH
Now I have to figure out why jumping from right to left still has the problem. I'm also a bit confused about how the dollyTransform needs to lookat the character instead of a point between the characters, but maybe that is ok.
I also seem to be able to run through the character and cause mirror to reverse without jumping when I'm near the character with ground collision mass set to 0.5 and scale 1 for character prefab. There may be accuracy problems with how mirror gets tested and set in ControlsScript. I think the accuracy or timing of when that gets set might result in a fix for the camera.
Perhaps the character is landing for a frame or two not rotated to the correct facing direction yet and the camera is trying to do a 180 rotation for a couple frames, but then it goes back to the correct position right away when the character is facing the correct way after changing mirror property.