Okay, putting it simply. If Jews were in fact mixed in with the other elements of the population, as they were, then your model doesn't really fit that well.
And we know that while a large part was in Prague, there were considerable numbers outside of it.
So somehow this developer has managed to mysteriously make a story where Jews are absent and Cumans are Orcs.[1] I wonder if this brand of whitewashing history might be deliberate, or merely extreme and unforgivable incompetence, especially considering the 'historical' selling point.
[1] There were likely fewer Priests in the area then there would have been Jews, but you don't see yourself arguing that if randomly somehow priests didn't show up at all in the story of medieval Bohemia, you'd be wrong to go, "Wait, what? Why?"