I got my hopes up when I discovered an "Import" option.
It can import as much or as little as you want.
It can import rules, units, cities, the whole map, and such.
...But if you import the map, it also imports the size. If you don't import the map, then the coordinates of the generated cities/units/etc. are off.
What would be actually helpful: importing the map, with it having a fixed appearance spot, without adjusting the map size.
Bottom right, I import Mesopotamia; top left, I import Napoleonic Era. Top right, The Middle Ages. Bottom left, Rise of Rome.
Or what would still be actually helpful: expanding an existing map's size, without losing everything. It'd expand things out from a point, mind you, but I could work with that; if it expanded out right/down, I start from Napoleonic Era and expand outward as needed. If it expanded out left/down, The Middle Ages is my starting point. Right/up, Rise of Rome. Left/up, Mesopotamia.
Yet to my knowledge.
The map will be the death of the scenario if I can't get this darn thing down.