Mod requests (orders).

You're suggesting I go through all the custom maps in the editor and also extract the standard ones? Great.

Well, then someone else will have to do it; it's all the same 🤷‍♂️
A script to replace towns can't be written quickly, by the way. Unless it's a Python script that also reads the terrain file (the one that describes the terrain) and changes the towns in the maps accordingly. That would be quite a headache...

I've been wondering about the black background for a while now. Is it possible to display a poster (artwork) on the screen instead of the black screen during the enemy's turn?

So that instead of blackness, various artworks from the game are displayed randomly.
For example, there are n artworks in a folder, and they are displayed randomly, one in one turn, the twentieth in another turn, the tenth in the third turn, and so on.

I don't know about random changes, but putting one specific artwork instead of the blackness is definitely not difficult. Judging by your screenshot. You need to change HotSeatBlackBg.xdb and either add a link to the artwork there or replace the xdb file with another one, in that vein. But I haven't checked, there might be some nuances.