That is correct in relation to the pilots perspective. But we are not talking about pilots perspective. The point to be made is that the model rolls in different directions upright vs inverted. What force changed to make the model roll the left wing down rather than right wing down. The only change is gravity is acting on the same wing panel. Warps and twist will go the same direction as far as the model is concerned.

Try holding right rudder and roll inverted. Yes the model will now go to the pilots left but it is still the right side of the model. Any corrective input (trim) that would be needed upright is the same for inverted flight. The air flow around the model doesn't know its inverted. Warps and twists, trim adjustments are all aero related. A model will not yaw left with the input of right rudder. It can only yaw right. Regardless of the model orientation right rudder creates yaw right with respect to the model.

I still think it is a Mass and gravity related force.

But then again I'm no expert.

Good luck with your problem.

Troy Newman