[Uberphallus]

Catastro doesn't have a clear license, but the spirit is certainly open[0]:

"It's worth noting the mass download service of cadastral information, available since 2011, that makes it free for companies and individuals said information, including the possibility of it being reused."

Translation mine.

I'd love to hear about the origins of such mysterious Ontario spot!

[0] http://www.catastro.minhap.gob.es/esp/usos_utilidades.asp

[freyfogle]

Without having looked in detail I would guess this is a situation where no license just causes confusion. Now it's unclear what is allowed. Ideally they would be explicit about what is allowed. Anyway, if it is allowed, using that data is a decision for the local OSM community. If you live there or have a local connection, please get involved, or just with mapping generally. It's good fun. Here's a tutorial of how to add house numbers to OSM, really it is pretty simple:

https://opencagedata.com/tutorials/adding-an-address-to-open...

re: Ontario, I will eventually have a look, but the list of projects is long and priority goes to bugs reported by customers.