>Do these agreements say that foreigners have a right to buy houses in Canada?

For sure.

https://www.international.gc.ca/trade-commerce/trade-agreeme...

CPTPP ensures that investors from the Asia-Pacific receive fair and non-discriminatory treatment. This means they must receive the same level of treatment as Canadian investors and any third-country investor in similar situations.

So Chinese investors can buy houses in Canada but if I am not mistaken Canadians cannot buy property in China. How does that make any sense?