You’re talking about prison. The claim from Vigano has to do with McCarrick and seminarians. Not children. To be clear, Vigano does not claim to have seen Francis cover up pedophilia.
He is making a claim that about sexual abuse in the sense of misused authority. Specifically that, that Francis lifted some sort of restrictions on McCarrick placed by Benedict because of conduct alleged by seminarians at some point… There is no record of that happening (Francis lifting any restrictions). Later when an allegation was made about McCarrick engaging in sexual conduct with a minor, Francis is the one who removed him.
Who is they?
Vigano’s entire claim is that homosexuality is the cause. And that Francis was lenient on a Priest that had engaged in/propositioned sex with seminarians. Not, that he had seen a letter about involving children.