FWIW - I've added a change you can make to the campaign_script.txt which relocates the heretics from the Med to northern italy.

(It's in post 2 of this thread.)

I'm not up-to-date with hotfixes, will DL latest one once I get to the TO emergence on my current campaign, so don't know if it's already been added.

(Playing through to observe a few other changes I've made, re spies in Ireland and garrisoned_armies in Ireland and Khwarezm.)