I think there were thousands still at that point, at least 5,000 maybe. Still nowhere near enough to handle the swarm, but could be a few Sorcerers on the far side away from the action scratched their way out of there with some others back to Dagliash ( and died still from radiation poisoning ) or somewhere. Nice to know someone was still up to recording history as the world fell apart ( images of the Titanic come to mind ).
Alright, a higher number than I thought, then (I honestly believed they weren't that many left, that's why I used "hundreds" instead of "thousands").
Very true, other sorcerers (or witches) could have facilitated some of the Ordealmen's escape. Even without the Metagnosis (pretty much restricted to Saccarees at this point, with Serwa in an uncertain state), that could work. I, for one, really hope at least one of the Swayali witches (aside from Serwa) survived. There were already so many missed opportunities there...
There were definitely still some people recording history, yes. Now, what happened
after the No-God started making his way throughout the Three Seas is (still) a mystery. Since TNG apparently will start a few weeks after the end of TUC, it's unlikely Mirathais and any others who survived would have been able to make their way back by that point. We have yet to find out if they all died during the Second Apocalypse anyway and the records were left for posterity, or...something else.