AI (diplomacy)
I was playing the Brits and was stinking rich, earning a zillion through trade and taxes. Every turn the Prussians offered me a trade deal in exchange of some money. That amount of money went up from 3600 gold to over 8500 gold twenty turns later. They were dirt poor and needed the trade, I didn't. More realistic would be (and in the interest of the AI) to lower that amount per turn of even offer the deal for free.

Winning conditions
You win a campaign by controlling enough regions in 1799. This means that even if you have captured enough regions in let say 1750 you still have to play until 1799 . Does CA really think that a human player who controls 50 regions is going to lose them during the rest of the game?