It occurred to me that Hans Judenkunig might have been a converted Jew (my somewhat elderly 'Grove' has nothing to say about his origins). Certainly converted Jews were frequently given names that made their origins clear to one and all. When the Jews were finally allowed out of the ghettos in the 19th century, particularly in Germany/Austria, they were allowed to purchase a family name. The less they could afford, the (literally) sillier (silly that is, in German) the name they were allocated. So poor Jews given names like Zwirnnadel (Threadneedle), or suchlike, while those better off were allowed to call themselves Rothschild. Only an idea, but the name 'Judenkunig' is so unlikely (certainly in my studies of German culture I've never come across one like it), that I just wondered whether this could be the reason. Cheers
Tom