well, at least in vanilla M2:TW it still has some very weird army composition (like armies consisting of militia units only, or, even worse, fullstacks of artillery). However, it is possible to have a lasting peace with the AI. hat generally improves diplomacy is that you can see what the AI "thinks" of you and your offers. the AI always keeps the balance of power in mind; it will attack those, who have not many allies and lots of enemies. this is why most M2TW campaigns start with a longe peacetime, until the first war breaks out somewhere; after the first war has started, europe will be in flames, since the AI tries to exploit its neighbours waging war somewhere else.