The editor supports a 4 time bigger map (twice as long, twice as high, roughly). The issue though is the huge amount of work. First, the map must be imported from War in Europe, then extended to the world, and I don't think you can do without hand placing the coasts one by one, among the 600 or so possible tiles! Must be mind numbing...
Plus as you nudge the map, you have to check ALL scripts.
So it is within the realm of the possible and the engine, now I don't know who will have the time and energy for such a massive endeavor. It would need a team.
AGEOD Team - Lead Developer
Makers of Empires, ACW2, EAW, WIA, WON