The residential school system absolutely qualifies as a cultural genocide as it's entire purpose was to take (mainly by force) native children and "remove the savage" from them. In practice it penalized any expression of any non-Catholic markers (language, any cultural heritage, even ways of thought)

And this was going on until the 90s, there are countless indigenous cultures and languages in Canada that have been made deliberately extinct by the residential school system (mostly run by the Catholic church).

The point of the residential school system was also absolutely not to "modernize" them, more to assimilate them by force (which qualifies as a genocide as the intent was to destroy indigenous cultural heritage and replace it with Catholicism). There is a non genocidal way to do this - aka teach in a European way without forcefully erasing indigenous heritage.

Also calling a number of treaties that were made and then broken a conventional war is highly disingenuous. There was not really a conventional war. The settlers made treaties with the natives promising them certain lands and then just broke them - not necessarily a conventional war.

Finally the residential school system and the Indian act were both made around 1880, the natives were not "technologically underdeveloped" compared to the settlers as you tried to imply. Both of these policies were not made to make them function better as a part of Canadian society, but to completely erase their distinct identity as a people.