Yiddish was in its infancy in this period and was not widely used across Europe for several hundred more years. Additionally, even at its peak Yiddish had very few areas where it was the majority language, usually being one of the largest minority languages in a region due to the dispersal of the Jewish population across Europe.
I've been really enjoying your language quizzes! It's fascinating to see different languages appear and disappear moving through the centuries. What sources do you use to make the maps?