I don't believe there was ever an official declaration that Mathurin was the sole prophet. In fact in his own time he said there would be others. However he never acknowledged another prophet in his own lifetime and disavowed at least one heretic who claimed to be one so declaring a new prophet became a very controversial idea in SA. ESA treats it more like Sainthood.
No, not officially, just 'accepted' amongst everyone in SA for many many months/years now.
Seoras paid attention to *why* Mathurin disavowed another and in fact, uses *those very reasons* as why SA has fallen in corruption. Mathurin disavowed Allison's OA because it was a personal glorification of herself, no worthwhile teachings, a political Church. That didn't mean there weren't still faithful within it, but as a Church Elder Establishment, it had been used as a tool of the theocracies' political hegemony and not vice versa. And ESA has always been strongly opposed to any Prophet self-declaring as being a sign of 'self-glorification'. And focused upon church/community improvement via the religious teachings
I would say ESA's sainthood is much more the Venerated than the Prophets. Those are hero characters who have died in battle, not only of ESA depending on roleplay, but are given a 'holy day' for annual celebration and remember of their life, that we may benefit and learn from their experience. Though I got lazy and I don't think I added the most recent, Draco Dogsbody, who came back to life like Seoras did.
