The cockpit instrument should only be operational in your own aircraft, because the CPU uses a lot of calculations to make these instruments display the way it is. When you have other aircrafts whether it is multiplayer or AI traffic. You don’t want the game to render and display their cockpit instruments, because it will take too much of your CPU power to do so, which will severely impact your performance.
That’s why the sim already locked these external models for Multiplayer or AI traffic, that they should not render the interior cockpit, and have none of the instruments operational.
I tried to override this before for my Live Traffic. I got them to render the default 747. And since the 747 isn’t designed to be used for AirTraffic, it renders the full cockpit with full instruments, and when I have 15 or so 747 being spawned at my airport. My sim becomes a slideshow, running at no more than 5 fps. I reset my 747 AirTraffic settings, and I’m back to 30 fps.