Raf:
Technically, the church hunts down and kills every human magic user it can find. Practically, the intensity of their searching depends on the order. Most orders don't search at all. Only the Witch-Hunters actively hunts (and sometimes secretly hunt other races, though they might be members of churchs the human Church associates with). Pacifistic orders like the Knights Ephestus might turn a blind eye if the person seems to be "misguided" rather than actually evil. A knight equenis could even work with a magic using type if the person was good enough a soul and he had a reason to excuse the person for not violating church law.
For instance, one of the playtest characters died during the second adventure (in act one, no less). At the end of the adventure they couldn't find a healer because in RM there isn't much in the way of channeling spells that heal intense brain damage. MacFlinn, however knew a 50th level lay healer. Although a lay healer would be a banned spell user in the church, he was a good soul and a member of a non-human race. So MacFlinn would actively work with him because not every race proscribes magic. So in his mind, it wasn't a matter for the human church. The Faerarch meets gnomish diplomats after all and many of them HAVE to know magic. I mean . . . they're gnomes. He swore the party to secrecy though. The Witch-Hunters would come after HIM if they found out.
All the magicians in Felric's Redoubt and Ludremon hide the fact.
I didn't know that about Kohler. Change the name if they go there.
I heard that Warhammer had a similar problem with one of their cities (Bogenhafen meybe?)