People should stay connected with the parts of their culture they retained when coming to America. You are not entitled to know everything someone is saying. This is a land of diversity, and that includes knowing different languages.
All I can say is that when my ancestors arrived in this country in the late 1800's from Poland, Hungary and Croatia, they made sure to develop a working command of English as soon as possible, and they always used it in public. They only used their native language when communicating amongst themselves. And I agree with that. I'm liberal on most issues but not this one.