Banned for using AHK and only 1 server-side action per button press???

No, you should get perma ban for using flask macro. If GGG wanted that we use all flask with one button they would implement this in the game. With using flask macro you can press all other buttons with easy, and have advantage over the people that dont use it.

If a lot of "big" streamers starts openly use flask macro i wouldn't be surprised to see this implemented in to the game.