Luther was a major force on the standardization of (school) German, wasn't he? It makes sense to me that his influence would have bypassed Yiddish. I take it to be mostly a variant of old regional German. I base this on transcriptions to the Latin alphabet that I have seen, for I have never learned the Hebrew alphabet.

Archaic language features: I have heard that Quebecois French was some centuries behind what is spoken in France.