RTF is a global modification that replaces all towns in the game.

in the cities of the Academy, from which the Elementals emerged, there have always been many demon worshippers and mages studying demonic monsters; perhaps without them, there wouldn't even be Orcs! For some time, Biara ruled the humans and definitely cultivated a large number of demon worshippers, and in the campaign for Zehir, there was a case of a human hero summoning demons, so it's all quite possible.