Leeneia, please note that the authors were born in Russia, of Yiddish mother tongue and Jewish "race" (by Nazi terminology), and apparently never saw Germany or spoke German.

Some Americans may nevertheless have associated Germany. As you know better than I, there were always many who had some romantic image of Germany in their hearts, regardless of their own ethnic backgrounds. We can see this again in the current Oktoberfest thread. (Actually hatred between the ethnicities of wartime opponents is rarely total, certainly not between Ukrainians and Russians.)

I like your idea of Hasenpfeffer, it makes more sense linguistically and culinarily than Ochsenpfeffer. Google even reveals a (partly) Yiddish ditty featuring the word – not a proof though.