When I refer to historical vs alt-history melting pots, I simply mean historical cultures vs alt-history cultures that result from melting pot events. Essentially my question being are there new, alt-history cultures that result from some melting pot events, or are there just different ways of getting historical cultures.

The list of melting-pots is available on our wiki: https://ck2.paradoxwikis.com/When_The_World_Stopped_Making_Sense#Cultural_melting-pots As you can see there are both historical ones, in majority, and a minority of alt-history ones.

Thanks for the reply.