Most wars in the era of the game were not total war - total occupation wars. Generally there were a few big battles and the winner would take a province or two, or even trade provinces.

You definitely should be able to give and take in a peace deal. For example, you win a war - they won't give you the province. But will they give you the province in return for a bunch of money, or a province of your own, or protection from anyone else who might try to attack them while they're down?

It would also be nice to be able to set your own truces. With a longer truce making the AI more likely to accept your deal, and stronger penalties for breaking longer truces. (e.g. a province with a 1 year truce = no, you'll just declare again. a province with a 5 year truce = sure, well be able to fight again then). Break a 50 year truce the day after you sign it? War with half of Europe's great powers.