I'm in process of making mod like you described.
The idea is to make all different tiles of one type the same (instead of random out of few different variants). By idea, it will decrease the chaos on the screen, making map objects more readable and the global view more constant-looking.

I wanted to ask, what part of the the game is more harder to percieve: global or tactical map?

Tactical map is a bit cluttered but okay global map is hard to perceive.

I think the same, was looking at aow 3 yesterday and i guess i realized what can be done. The first one that will take my attention will be global map.