I have well over 1,000 78's and probably about as many 45's. I don't have any by the Comedian Harmonists, but I do have their 1930 recording Wochenend und Sonnenschein (Weekend and Sunshine)--the German version of Happy Days Are Here Again--on CD (I have at least nine versions of Happy Days Are Here Again).
Three were Jews, three were not. Hitler broke up the group, I forget when, 1934 or 1935. All six survived the war but they never got together again, and never really got friendly again. The last died only a few years ago, in Palm Springs, CA.
The Harmonist were inspired to get together in the first place by an American group of the 1920s, I think called The Revellers -- a sophisticated group described as barbershop with a college degree. I have a couple of things they did on Retro CDs, "My Blue Heaven" and one other I can't think of.