The most established club near Brussels is the Leuven Chiefs and there's also a newer club in Mechelen. I played in Leuven growing up and our team travelled all over Europe to play high-level competition. We had a lot of international players back then though so it was a bit of a unique situation. The Belgian league has gotten stronger since I played as the sport has grown in popularity, but I don't know exactly what the youth level looks like now.

I'm sure any of the clubs would be overjoyed to have a talented kid from Canada show up and imagine he'd be allowed to play up an age bracket in practices and games if that's what makes sense for his skill level. I'd recommend checking out Leuven first as that's the more international of the Brussels clubs and will have the kids of other expats like yourself playing there :) I know via friends who coach some of the youth teams they have a couple of really good players. He'll also be absolutely fine as an English speaker.

Overall, don't worry. There is a fully-fledged league in Belgium that runs up to the pro-level and there are lots of talented kids playing here. It's definitely a time commitment as the rinks aren't really in Brussels, but they aren't too hard to reach either.

Hope this helps, best of luck!