Which hand on which control is getting too much thinking. My two certified planes each have the throttle in opposite hands when flying in the left seat, no problem. Don't think of flying the plane as thinking your left/right hand to move a control to fly the plane, think to fly the plane, don't think about what your hands are doing, they'll figure it out soon enough. It's like children, don't let them complain about something being different, just let them do it as normal.
For anyone who has ever learned to operate a backhoe/excavator well, you don't make your mind operate your hand to operate a lever to operate the boom or the bucket, you just make you mind operate the bucket, forget what muscles are in between. I'll watch myself trenching as intended, and look at my hands, they're just doing their own thing, as my mind moves the bucket. 'Same with the plane, I think, it flies, I don't care which hand is doing what.