The Court has declared aboriginal title to your property

Do Canadian title insurance regulations really allow the insurance companies to not provide coverage for indigenous land claims? That seems completely irresponsible.

And "due diligence" doesn't mean a homeowner must sift through two centuries of title history and determine the validity of the title themselves. Otherwise that would be a requirement (or to pay someone to do so), just like title insurance, except a lot more expensive.

And due diligence may be wrong, or right but still contested, so it goes to court. Title insurance helps pay for that title defense.

So yes, when I bought my house in the US on what was once indigenous land, I was quite aware of the possibility of title claims, but indigenous treaty law for that land goes back to Imperial Spain, incorporated into US treaty law, and researching that is far beyond due diligence.