In my first year of campaign (1880) there are many wars in Europe already - Austria attacked Switzerland, Ottomans attacked Bulgaria, and Russia attacked Romania. Is there any way to make AI less aggressive? This doesn't seem very realistic.
It will work...from now...won't affect the already declared wars...all you need to do is change the values (the figure are a percentage chance to consider the action described, in absolute, i.e. War 50 means 50% likeliness to consider a war...provided conditions are ripe).