Actually, the Federal Court was clear. Neither the panel nor counsel for the ministers, whether for the Canada Border Services Agency or Immigration, Refugees and Citizenship Canada, get to choose the language of proceedings. The choice belongs to the client, the claimant, who must choose whether to proceed in French or in English. The right to proceed in either of the two official languages belongs to the client and to no one else, certainly not to the panel.
As soon the client expresses the wish to proceed in French, the panel must accommodate that decision and provide services in French. Documents must therefore be submitted in French, and, if the claimant does not have a command of either of the two official languages and if everything must be translated into their first language, an interpreter speaking French and the client's first language must be assigned to the case. That, fortunately, was the Federal Court's ruling.