French FAs speak French. They all have some English skills, some good, some just basic.
If they learned another language in high school, or have some non-French family origins, they might speak other languages.

On longhaul, AF tries to make sure that there is at least one FA fluent in the destination language (i.e. Japanese for Japan, Mandarin for China or Mandarin+Cantonese for Hong Kong, ...). On LAX-CDG you will be sure to have at least one FA fluent in English, and all with reasonable to basic skills.
Don't be fooled by their good ability to address you with good English in the several sentences basic to their service. Asking fast and complicated English questions might not be fully understood by some/many of them.