Hi Galium,
I can't help with your actual research, but I thought it might be helpful for you to know that Kasendorf, Oberfranken and Kasendorf, Bayreuth are indeed one and the same place.
It is a little village (Dorf = village) in the district of Kulmbach (famous for its beer

), about 20km away from Bayreuth. This comes under the administrative district of Oberfranken. And is in the State of Bayern (Bavaria). Bayern is a Freistaat, which is a kind of republic. They have laws which differ from those in other parts of Germany - including concerning public holidays. A bone of contention here...

People from Franken do not like being called Bavarians. Many years ago, I had a boss who was from Franken - and woe betide anyone who said he was from Bavaria!

Anyway, this Kasendorf is about 200km from Leipzig.
The Casendorf up north appears to also be written with a "K" in modern times. It is about 400km from Leipzig.
But as you say, people travelled to certain places for work, so the distance from Leipzig might not be important.
What online sources do you have regarding his birthplace? It could be that someone googled Kasendorf and came up with the one up north...
Best regards,
Karen