En France, l’évaluation des compétences linguistiques ne portera que sur la langue française et sur la langue anglaise, qui sont les 2 langues utilisées par le contrôle aérien français. Les pilotes désirant obtenir une compétence linguistique dans une autre langue (espagnol, allemand, russe, etc.…) devront s’adresser à l’autorité d’un Etat organisant les compétences linguistiques en cette autre langue.
This means the DGAC will assess French and English proficiency (which are the only two approved languages in French aviation) but for other languages, pilots have to address other organizations (this actually implies that the French license issuer should accept such foreign assessments). The law text mentions how pilots get the French level 6 entry. The law also clearly states that one has to have the relevant assessment for the language used.
I don't see anything in that that says you must have French proficency in your licence to use a French only airport, or to speak French on the radio.
Is says that the DGAC can test one of their pilots for English or French. If a pilot wants a languange proficency in another language then the DGAC is directing them to another CAA.
The actual law text is here.
Perhaps rather than asking me to translate nine pages of French law, you could direct me to which part of it you are stating is the law requiring a French languange endorsement to use a French only airfield?