I knew a Hungarian couple like that. After they fled Hungary, they made their way to the US, but slowly and in stages. The couple made the effort to learn the languages of the countries they stayed in. The wife ended up being nearly fluent in French, German, and English.
Yes, obviously he spoke French and was able to teach it effectively.
I took his class for all four years. Then I got out into the world and realized “nobody WANTS to talk to those people!”