Oh heck no...never heard of a Welsh family there. Verdun was at the time a newish working-class residential area of more or less equal French-speaking/English-speaking population...I suppose more to the French side...and Irish. Lots of Irish there, although the poorer ones were in a couple of nearby neighbourhoods. So the French and the Irish and some of the general English-speaking mix being Catholic, and only the non-Catholic English-speaking residents being various denominations of Protestant, a Welsh Presbyterian family would have stood out. Today the tension is a French/English issue, but back then it was a Catholic/Protestant one. My dad said there used to be fights between the French Catholic boys and the English Protestant boys after school.
It was by no means a Shankill Road situation. Just schoolboy fights really. But it was a feisty neighbourhood and a Welsh family would have been an unusual addition. The preferred destinations for Welsh emigration were Patagonia and Welsh colonies in America. Not Montreal, and there was certainly no Welsh neighbourhood there. Makes me quite curious why they chose Montreal

Cheers,
China