1) When talking about the canon of Scripture, veering straight off-topic and throwing the bloody chum about queers and pedophiles into the sea is shark-bait, not advancing the conversation.
People who betray Catholic faith and morals, do damnable things. How is that new, or even relevant? The 46 books of the OT show God's Chosen People with regular frequency abandoning the Lord and whoring after World, the Flesh and the Devil. That does not mean that God's Prophets were no longer God's Prophets, nor that God's Laws were no longer God's Laws.
What it means is that, then as now, when you're do God's will you're blameless, and when you don't, you're not.
In other words, the betrayers of the Church are not "the Church," and the infidelity of those who betray the Church does not cancel out God's fidelity. The Church is not the Mystical Body of Francisco Coccopalmerio or Ted McCarrick or Jorge Bergoglio, it's the Mystical Body of Christ.
2) Rome was not the "capital" of the Church because it was the capital of the Empire. Rome, a crumbling city even by the third century of the Church's existence, lost its political hegemony very early indeed, when the brilliant city of Constantinople was made capital in the East, followed quickly by he sacking of Rome by barbarians in the West.
It was not renowned as the greatest city. Even Alexandria surpassed it. I was renowned because it was the city where SS Peter and Paul were martyred, Peter being at that time Bishop of Rome. (He had previously been Bishop of Antioch.)
The formal structures for carrying on St. Peter's ministry have shifted significantly over the centuries, and his See has been occupied at times both by saints and scalawags.
This does not negate the precious promises of Christ, in Whom I put my trust, that He would be with us always. He is God, and can neither deceive, nor be deceived.
Which would contract the RCs who denigrate the one true church as being the Mystical Body of Christ, since unlike the visible body, it always and only consists of true believers at any given time.
Except that certain papal teaching is that the Mystical Body of Christ and the Roman Catholic Church are one and the same thing, with the necessity of belonging to the true Church in order to gain eternal salvation, thus excluding those without.