With the High Septon's recently gained powers that will probably change in the next books.
Good point. I'm thinking the best solution will be to have no heresies at all in the mod for now, and we can add some if/when GRRM has the high septon become a grand inquisitor.
On the subject of religion, I know it's been discussed before, but how do we want to set up the religions/groups? I'm thinking the Seven and the Old Gods should probably be in the same group, and R'hollor should be a separate group. What about the Drowned God? On the one hand, it's as alien as Rhollor to the "mainstream" Westerosi faiths; on the other, I don't remember the same level of hostility between it and the Seven as there is between the Seven and Rhollor. I'm thinking a separate group makes the most sense, but don't allow holy wars between the groups.
In fact, I'm thinking we should get rid of the holy war CB altogether, or restrict it to the followers of Rhollor only. As for crusades, again, I think only Rhollor should have them.
What about heads of religion? The High Septon fits the Catholic/Orthodox mechanics well, but none of the other religions have obvious heads. Should they all just use the pagan mechanics, or should we designate someone as the head of the religion. I could see Stannis or Mel being the head of the Rhollor religion, so perhaps Muslim mechanics, where a secular ruler with a claim to be Azor Ahai is the head of the religion.