Added a rough event chain that goes through an establishment of some kind of League of Nations or maybe something else...
League of Nations:
After a great war a nation may propose the league of nations.
If a great power decides that restricting war isn't good then it'll lead to a war between those that want it and those that don't, if there are any that don't. Upon winning there will be a global infamy reduction modifier.
If the league passes to the voting stage then there is the option to keep it as is, so nothing changes, or to found the league. On founding the league there is a global infamy malus but an increase in diplomatic weight (I have read that despite implementing it properly the paradox code behind it might mean the diplomacy buff doesn't actually work)
If 1 nation votes to keep things the same, the league doesn't pass, as such the AI will never pick this option.
Bug fixes & changes to infamy costs
In or after a great war, with high war exhaustion you can found a tomb of the Unknown soldier/warrior.
Added inventions to the psychology path which increase the amount of diplo points you get
Added inventions to the Art tree that slightly increase war justification efficiency, getting all three in 1 tech allows for a 1 time event that reduces your infamy by 3. Getting the last event gives a modifier which reduces your monthly infamy by 0.05