Thanks for your reply.
At first, I suspected that the story of my grandfather's internment in a prison camp might have been publicity (to glamorize the relationship between him and Kalanag / Schreiber). However, there is some historical evidence to support the story: I have found his name (given as "Alfred Mihiel", his legal name) on a document relating to POWs detained in Germany. Neither of my great-grandparents was Jewish on that side of the family; his internment may have been related simply to military service of some kind.
Unfortunately I can't confirm or deny the Frakson story, but I believe that it is most likely a fiction, because Frakson never appeared in my family's (extensive) discussions of our genealogy.
As I heard it, the origins of the name "Mihiel" are as follows: my great-grandfather (Olten's father) had been abandoned on the proverbial church steps, or at an orphanage of some kind, as a baby. He was "found" on the day of Saint Mihiel. The Catholic institution that took over his care gave him the saint's name as a family name. In contrast with these humble origins, my grandfather sometimes gave himself the title of "Count" in his stage appearances.
I will contact you off-forum, and look forward to continuing the discussion.