Hey!
This is actually pretty decent and detailed feedback.
As for custom mods, they’re harder to download on a mobile device, and they’d be subject to an additional level of supervision, as well as a whole system to create and apply those liveries across multiplayer. Perhaps that might be a future thing. In fact there’s a feature request for it here:
I would say, just be patient. Improvements will come in time, with scenery and aircraft reworks (and new aircraft hopefully), as well as more and more 3D airports, and more and more new IFATC members filling up the airports, so more regions are covered at any given time. The pace of technology too is pretty speedy, so I’m sure that it’ll catch up as well.
However, that being said, one can totally understand how waiting for these things for a long while can put a pinch on your wallet, and it makes financial sense to come back at a time when in your opinion, you see a significant improvement in the game.
Hope to see you back in the game at a time when you see fit to return and pay for a subscription again. We’ll all be waiting 
Cheers!
-Sooraj