
spikadelia |

My guess is that they would have been based in Nerosyan since the place of worship was large enough to be called a Cathedral. As to what happened....
In Council of Thieves pt 4 the relevant chapter says:
4665, Kuthona: The Order of the God Claw abandons the Leaden Cathedral in Mendev at the start of the Third Mendevian Crusade. Returning to Cheliax, the Order of the Pyre sponsors the small but wealthy order. Construction of Citadel Dinyar begins soon after.
I'm running WotR and decided that a small enclave of Hellknights (mainly an uneasy alliance of Order of the Godclaw and Order of the Gate) remained in the region and chose to base themselves in Kenabres at the Galenic Chapel. With the events that take place at the beginning of the AP they retreat to Nerosyan.