Spent two years in Germany courtesy of US Army. Two local siblings (girl and boy) hung out with us some nights at a local bar. Both spoke very good English. She was attending University in a program that prepared her to teach English in the German school system.I took German translation a year ago, and one thing I learned is that there is almost always translation loss. When there is more than one or two words at play, it can't be helped. All that a translator can do is try to minimize it. That 400 level course was enough for me. I'm not even going to attempt the masters certificate. It's really a lot harder than a lot of people think.
She learned the English straight out of the book in class. Our slang and accent depending on which parts of the states we were from invariably through her off and needed clarification.
Everything does not translate from language to language.