[Ygorl]

Arralen, external AIs (of many types) could work. You'd have a program that would take as input a .trn file, a .map file, and any .mod files in effect (if you were feeling mod-friendly). It would do its thing, and give back a .2h file. Now, training some types of AI could be harder, since it wouldn't have direct access to the battle resolution engine; it still wouldn't be impossible though (remember the battle simulator from Dom2? Or it could create a microgame on a special 3-province AI-map to test strategies, much as real humans sometimes do...)