I'm sure others will have much better information than me, but I'll
give you what I know.

My "Hungarian" relatives are all >from Slovakia, though many moved to
Budapest in the early 1900's. I was surprised to see several mentions
of German being the native tongue in various documents, as well as
finding some vital records in German.

I tracked down a cousin I didn't know about and have chatted with her
on the phone a couple of times. Her grandfather is >from Slovakia (b.
1863, moved to US in 1890) and, when he got very old, he reverted to
only speaking German. I asked, so he didn't speak Hungarian or
Slovak? Nope, just German (not 100% clear that he didn't *know* those
languages, just that he didn't use them at home or regularly...though
I'm not sure what he spoke in school).

On the other hand, my grandfather (b. 1900, immigrated 1939) (who was
the above relative's nephew and this was a close knit family) spoke
Hungarian. If he also spoke Slovak or German, I never heard of it.
He moved to Budapest as a young man and my mother was born there and
she only spoke Hungarian with her family. My grandmother (>from Kassa/
Kosice) is the one who had German listed as her native tongue on I
think it was her passage over.

I don't know how much of this is because of the "Austra-Hungarian
Empire" where German was a major language vs any of our relatives
being, in fact, "German Jews." I also don't know how the various
countries treated Jews, compared to each other, or if there was
prestige in being associated as one or the other. Nor do I know if
non-Jews in the same areas spoke German. In your GGfa's case, it
could be simply that he moved.

Cyndi Norwitz