If I recall, it may well settle out all wars with Russia, France and the UK including any extra ones that are going on. In my game it stopped a war between Prussia and Sweden (though that might have been coincidence).
If so yes, mod the event so its not white peace = all or a similar syntax.
But then I think as it works its reasonably historical, the Paris Conference was one of the last attempts to maintain the 1815 Congress of Vienna model of all the powers settling all existing disputes, so regard your peace with the evil Prussians as a side effect.
More generally I had a go at some of the Russian events up to the 1860s, some notes are in this thread:
viewtopic.php?f=345&t=53576Somewhere I also posted a fix for the problems with the Caucasus revolt, there is something odd about the counter of its leader and the attached unit that sets off a crash when you attack it. Can't remember now where I did this, it might be lurking in my partial Russian AAR.