Mixing physics overwrite with physics simulation will give you some weird glitches down the road.
And you break physics each time you rotate it trough blueprint directly.
Your original problem started because you do not understand basic kindergarten problem, that is how do i rotate carousel.
You applied only one force (because unreal physics simulation is not perfect) and on top of that you applied it near center of mass.
No wonder that guy did not rotated.
To rotate with physics you need 2 THRUSTERS (because they do not need per tick action), put one ahead of character one behind. Both should face to right side, and autoactivate. Set forward one strength to +something and rear one to -something, it will nicely turn.
Then calculate normal of ground surface below character, by tracing 3 points and doing cross product. When you have normal vector, project it on flat horizontal plane, you will have direction vector of slope, calculate angle (from up vector [0,0,1] and your slope vector dot product of them is cosinus of that angle). From cos calculate pushing force. Add that as force (or thruster) to your character.
So either go full for scripted trough blueprints movement, or go full physics. Do not break physics simulation with overwriting location or rotation values.