I don’t see this as any type of barrier to admission.
– No college I know of requires foreign language past level 4 so she will be fine in that regard: and
–She can ask her guidance counselor to mention the scheduling conflict in his/her LOR. It is a fairly common occurrence.
I can’t recommend the best way to continue French (perhaps a CC or online class only if her schedule permits – keep in mind that filling out applications will be time consuming) but hopefully others can chime in.