Empathy makes the bilingual speaker protect you from suffering with their language, and it makes them too helpful useless.
What you need is to try. But people aren't like that. They'll protect you.
The tendency to speak in the most-convenient language is powerful. Communication is primary, and this overrides all appreciation of your effort. A person who speaks English will switch to English. If you're serious about learning another language, it will happen faster than you'd like.
This is probably true of any lingua franca. It's certainly true of English.