That is very interesting; in dealing with Quebecois and Puerto Ricans, I’ve noticed what you describe: While they may use the incorrect tense, they can make themselves understood. They all learn English in school but use French/Spanish in their everyday lives.
I was in Quebec City back in April. I’m used to Nicoise French speaking heavily accented English. I must admit it being disconcerting to have someone speak to me in French, who upon realizing I didn’t speak it, immediately dropped into perfect North American standard English. Not everyone there, of course, but enough that it happened several times in the course of a week.