Judges often sit on a case relating to a matter that isn't their speciality because judges hear a wide variety of cases. Often somebody who had been a real estate lawyer before they became a judge is all of a sudden hearing a family law case. This is a very common thing. It's why judges require training. It's why important institutions like the Canadian Judicial Council exist to provide that training.
Because of the immense, significant gap between what judges understand and what the reality is of intimate partner violence, this is one of those things, as with sexual assault law, that requires specification to judges that they undertake this training if they are to become a superior court judge.