He needs to hire a Karen for language.
The best Karens in education wore nun uniforms and carried rulers and yard sticks as their rod and staff of authority and retribution.
A year with a Karen correcting his speech and he’ll be as proficient as any born native speaker.
I did 10.5 years of Catholic school...with many of them having French lessons.I learned almost nothing.Listening to a French person speak I’m lucky if I can pick out 1 word out of 20.