If you look at the German version of Wikipedia (under "Ziehharmonika"), there's reference to an accordion builder called Heinrich Wagner who was active in Gera in the late 19th century "1890 wurde die Firma aufgelöst, der Markenname wurde von der Fa. Buttstädt übernommen" - in 1890 the firm was dissolved, the brand was adopted by the company Buttstädt. So there does seem to be a connection between the brand and Gera. It may of course be a complete coincidence, but it also seems that a significant 20th century industry in .Buttstädt. was the manufacture of ear protection devices.....