I received an inquiry for information regarding zither maker A. Koffend. Does anyone have anything to share?

Here is the note and images provided:

I have a zither that my mother learned to play while attending school in Austria at age 8. My grandmother and she went to Austria for a year in 1933 while my grandfather stayed in the U.S. and worked.  [My grandparents came to the U.S. from eastern Austria in the early 1920s.]

The zither was made by A. Koffend in Wiener-Neustadt.  I can't find any information about that instrument maker and wondered if you have heard of it. I attached a couple of photos.