I've always pronounced the word "Southern" to rhyme with howthurn. I know most people say it like "suthurn" instead. I didn't realize that the way I pronounce it is considered weird until recently!
Living in Los Angeles as a white person, I refuse to pronounce street and city names that are Spanish the English-speaking way. Knowing Spanish since I was a kid from school and using it on a daily basis, my brain simply doesn’t butcher the pronunciation by default.
It’s caused confusion though for sure. I used to live near a street called La Tijera, but Americans pronounced it almost like Spanish “la tierra” which is a completely different word, and I couldn’t figure out where this street was that everyone was talking about.