Hi i talked to my boss’s wife today about the cafe and she said she hasn’t heard of it and that perhaps they are not in business anymore, which isn’t weird since the tray dates far back. What she could say however is that Klagenfurt is a city in the south of Austria and that the person that opened the cafe in Vienna (wien) must have their roots there.

What I’m thinking is that you could always find one of the more popular/old cafes in Wien and contact and ask them if they have heard about this cafe place and perhaps they will know a bit more of its history.