«The “doctrine of discovery” is not part of the teaching of the Catholic Church».
True, it isn't today.
«Historical research clearly demonstrates that the papal documents in question..have NEVER been considered expressions of the Catholic faith».
Well.. 1/ press.vatican.va/content/salast…
The tricky point is precisely the focus on the "Catholic faith". Historians have never claimed that those Bulls had a dogmatic value: they didn't teach doctrines one had to believe so as to obtain salvation. Their value was legal: sources of international law for Christianity. 2/