Very minor, but can the popups be removed? So often they are completely wrong as after all events have changed since the history in this reality.
Are / can troops be fixed to the ownership of privinces? That would enable an empire that is on the steppes would have few infantry (they have little use on the steppes) BUT as the same power conquers other areas they would see the purpose of infantry and would then be able to build them.
ghengis Khan was renouned for his cavalry in the mongolian steppes, but when he had conquered vast swathes of China he altered his tactics and attacked Japan with an army mainly based around infantry.
Another option would be discounts if provinces were owned thus making it possible to fight the trend but would be extremely inefficient.
Just a thought...