you need to be quite close for him to trigger, maybe on middle of an island you have traveled around? he is supposed to spawn close to inner circle, about where meadows begin to have draugr villages. always in black forest. look for those medium large full black forest islands.

if you wish. you can look at the map online. if thats to much spoiler, you can share the seed with someone and have them look and then make you some kind of riddle to find him, or vague description of his loc.