As a Catholic who has pondered the Sola Scriptura belief a great deal I have to say that first, we Catholics have to put aside the notion that Protestants are willfully ignorant had are deliberately choosing to follow a path that does not lead to Salvation. Quite frankly, I have found many Protestants who love Jesus and God more and live their lives in greater harmony with the Gospels than many CINOs. There is a lot we can learn from them too.
I see the Sola Scriptura movement largely as a failure of trust in the Church and its Apostolic Tradition. When you know what they believe about the Church and its history it is more than understandable, it is expected. They see this as having to rely on the word of an institution that they believe is evil. Were the distortions and mischaracterizations they state true I too would not trust the Church.
We know that the Scripture proceeded from the Tradition and that for 300+ years there was no Scripture beyond the Old Testament. Remember, that the Canon of Scripture given by the Church is largely accepted by Protestantism. When they cite the Bible we need knowingly ask "says who" since the Early Christians could not agree on whether Revelations and the Epistle of Barnabas should be in or out.
We Catholics must therefore, with patience and love, correct their errors and overcome their doubts. This must be done with objective facts, respect, and the example of beatitude.
I wonder what makes you think that these folks WANT to be corrected and that theirs ARE errors. They actually have NO doubts as to THEIR faith.
Respect, etc., are nice but I don't assume to correct people who don't WANT correcting because THEY don't think that they are in error.
Change has to come from WITHIN. People will change only when it hurts more NOT to.
Thank you.