> Don't make it like nonplussed, where Americans gave it a new meaning out of stubborn ignorance

I do believe you are mistaking how the English language works for stubborn ignorance.

There are many dialects of English, and the way I speak mine doesn't change how you speak yours.

It's very colonial of you to think that your way of doing things is the best and must be forcibly pressed upon others. That you feel embarrassed by the (correct!) use of a word in a different dialect means you have some work to do on yourself.