If we look at the provisions, it's paragraph 530.1(f), “the court shall make interpreters available”, etc. My understanding is that, say, we're conducting a trial in the French language, the accused has asked for a trial in French, and there's a witness, an anglophone, who has a right under paragraph 530.1(c) to testify in his official language, he will do so. The accused can then ask for, and the court will have to provide, interpreters for the accused so that he can hear the live translation of what that witness is saying.
On May 27th, 2013. See this statement in context.