There haven't been any official complaints as far as I know.
I have to say though, as I indicated at the outset, that the Values and Ethics Code for the Public Sector and the department's code of conduct very much encourage informal conflict resolution. Some individuals might not have been heard, but that may be a matter of perception. For example, as you can see on the screen, the person speaking is in a car. The interpreter may say that he or she can't really hear what's being said, while others in the room may reply that they can hear the person loud and clear. That can make interpreters feel their judgment is somehow being questioned. I've heard of cases like that.
As for official complaints, Ms. Trépanier has been with the Translation Bureau longer than I have and can give you more details on that.