Regular townies turning into spellcasters?

I have a side save in which I am currently designing my own spellcaster townies. When I am done with one I mark them as unplayed. When I make a brand new spellcaster I run into my earlier creations in the realm. Trying to get a feeling for how many townies I need.

I really like this feature of only spellcasters coming to the realm. It is possible to go to the gallery and download a few spellcaster if one doesn’t like to make them by yourself.