Sworn translations are a special requirement
For official procedures in France, ordinary translations are often not accepted. Documents such as birth certificates, marriage certificates and diplomas may need translation by a traducteur assermente, a translator certified by a French court of appeal. Agencies in your home country may sell "certified" translations that French offices later reject. If a French authority such as CAF or the prefecture will use the document, plan for a sworn translation, which can also be arranged from within France.