I would say that even in our own language, it seems as though sometimes some judges do not understand our arguments, but I do not think it is necessarily a matter of translation.
In New Brunswick, the question is moot. I have always practised with bilingual judges. If it was known that a case was proceeding in French, in English or in both languages, the judge hearing the case was bilingual. I've never had to resort to interpretation for a judge to understand me. I've sometimes had simultaneous interpretation of witnesses' comments, because it was available to the parties who could not understand the other official language.
In New Brunswick, colleagues are very tolerant when we are presenting our arguments. However, take a case where the judge and myself are bilingual and my colleague is unilingual. Generally, the interpreter will whisper into my colleague's ear so that the flow of my arguments is not interrupted by interpretation. People are very tolerant and respectful, in New Brunswick.