Interesting, I had thought that since Germany + Austria-Hungary and Russia + France demonstrated a collaborative Human-AI behavior, that this could be extended to other countries as well. However, as is more often the case than I'd like, it seems I was mistaken.
So does this mean that there is a specific AI script responsible for each combination of AI-Human within an Alliance for the 4 player GC (i.e., one for Human Russia, AI France; another for AI Russia, Human France; another for Human Germany, AI Austria Hungary; and finally one for Human Austria-Hungary, AI Germany)?
If so, in order to make this work with other nations, that is a lot of scripts indeed to handle all possible AI-Human combinations for all the nations in the game.
Of course, since I'm just guessing about how it works again, it's entirely possible that I'm wrong yet again.
Reason I asked about this was because I'm still learning the ropes of this game, and I figured a good way to learn the basics (apart from the extremely short tutorials and smaller scale scenarios) was to control just Austria-Hungary, as they aren't generally even involved in the Western Front.