As far as I can tell, you are claiming that there is a viable model in which, for example, a charged object moving in an electromagnetic field would have "zero proper acceleration" while an uncharged object moving solely under gravity, would have "nonzero proper acceleration". But such a model can't be right, because "proper acceleration" is a direct observable, and our direct observation is the other way around.
It is so difficult to remotely understand all this when every other term is in "quotes". Of course, I'm not a physicist, so I probably wouldn't understand it all, anyways. I am just pointing out how many dang quotes there are. Could you guys maybe define the terms first so you don't have to put two fingers around every concept?
BTW I made this "comment" by "clicking" on the reply button and then I "typed" it using my "keyboard". No, I don't mean "keyboard" when I say "keyboard", hence the quotes.