I would be greatly tempted to answer yes.
We are talking about the language ability of judges. At the time of selection, they are not subjected to the language ability test. Lawyers fill out a form and it is up to that same person to say, yes or no, if they consider themselves to be sufficiently bilingual. There is not even a discussion of whether or not they are functional in the language. It is French and English and that is all.
On the contrary, I would say that if we insist on the ability to understand both official languages, afterwards, at the time of the hearing, it would be a much greater incentive for the person who was perhaps more or less bilingual at the time of their appointment to continue their language training specifically to be able to hear all of the cases that come before the Supreme Court of Canada. Once the choice is made, the candidates say that yes, they are bilingual, but their language ability is never really challenged afterwards, if they can make use of translation and interpretation.