Probably the same way Germans would feel being told “Ich vergessen” is Yiddish rather than bad German.
Yiddish is a jargon that combines Hebrew with a variety of European languages. Yiddish varies depending on where the Jews lived in Europe. The Sephardi speak Ladino, which is Hebrew mixed with Spanish, Portuguese,and other Southern European languages.
In my own family, my Ukrainian grandmother and my southern Russian (we think; the information was always closely held away from the American-born)bickered forever over pronunciation. As kids, we simply said “braedt-brodt” and “pitter-putter” at home to avoid arguments and get what we wanted at the table.
And if that wasn’t bad enough, the Russian Jewish recipes differed enough from the Romanian Jewish recipes (or whichever other country)to engender incredible snarks in the kitchen between female in-laws.
On to Christians: my husband’s aunt spoke High German. Her housekeeper spoke Low German. For 40 years, the aunt would pretend to not understand a word the housekeeper said, since her German was so *terrible*. The housekeeper, of course, also understood the aunt perfectly. It was ridiculous and everyone laughed about it except the two ladies involved.
My father grew up speaking Yiddish, Argentinian Spanish, Hebrew, some Lithuanian. He didn’t speak English until he was nine. He said that during WWII his Yiddish got him through the Netherlands and Belgium quite well. His Spanish was close enough to the street Spanish he encountered in the Philippines that he could communicate.
I still need subtitles to understand many English dialects.