You write, “If St. Paul wanted to say that it is sufficient — including the scripture not yet written — he would have said so, and he didn’t. Don’t spin, read.”
I did read, Tornado. He wrote that it teaches and rebukes “so that the man of God may be thoroughly equipped for every good work”. That defines sufficient. I use the word because it is easier than writing out all the full quote of Paul. If a manual teaches you well enough that you could be thoroughly equipped to perform a deed, is it sufficient to teach you the deed? That isn’t spin or interpretation, just basic English.
“but who, according to St. Matthew and St. Paul is the foundation on which we resolve disputes about the meaning of what He said?”
According to Paul, we should take our doctrinal disputes to the overseer. “He must hold firm to the trustworthy word as taught, so that he may be able to give instruction in sound doctrine and also to rebuke those who contradict it.”
Notice, they had already taught the trustworthy word needed for sound doctrine. They didn’t need to wait for 500-2000 years for the Magisterium to unfold new meaning. Paul had already passed it on. As he told the overseers in Acts, “I did not shrink from declaring to you the whole counsel of God. 28 Pay careful attention to yourselves and to all the flock, in which the Holy Spirit has made you overseers, to care for the church of God, which he obtained with his own blood. 29I know that after my departure fierce wolves will come in among you, not sparing the flock; 30and from among your own selves will arise men speaking twisted things, to draw away the disciples after them.”
Jesus doesn’t address correcting church doctrine, but since you mention Matthew, I assume you are reading Matthew 18 out of context. Also, realize the word translated ‘church’ means ‘assembly’. It had started to take on religious tones, so ‘congregation’ would be a better translation than ‘church’. We’ve been stuck with church since the KJV, where King James, for political reasons, order the translators to use church instead.
I wrote, “it DOES mean that we should reject the “unfolding” done by the Magisterium for the last 2000 years”. When you reply “How?”, I assume you mean how does it mean that, not how does one do it. And it means that because if Paul taught the full counsel of God, then it would either be found in what was written, or in an oral tradition passed on from bishop to bishop - NOT discovered or ‘unfolded’ by men hundreds of years later. If it was the FULL counsel of God in 60 AD, it didn’t need men to find more in 1200 AD.
It does say that the clergyman is thoroughly equipped, but it does not say he is so solely because of the scripture.
should take our doctrinal disputes to the overseer
That is spin already: the word for "overseer" is bishop (episcopos, Titus 1:7f, from where you quote), that is a man of the Church, which is also directly indicated in Matthew 18:17f.
the word translated ‘church’ means ‘assembly’
Not in Matthew 18, where the "ekklesia" is capable of rendering definitive judgement: it is "two of you", the apostles, not for example, the offending brother and the assembly of HIS choosing. For Matthew 18:17-18 to make sense the "ekklesia" has to be not just any assembly, but an established one, lead by a bishop.
They didn’t need to wait for 500-2000 years for the Magisterium to unfold new meaning [...] if Paul taught the full counsel of God, then it would either be found in what was written, or in an oral tradition passed on from bishop to bishop - NOT discovered or ‘unfolded’
What new meaning? It is not the task of the Magisterium to develop any new meanings. What the Evangelists and the Apostles taught (not just St. Paul alone) orally or when neccessary in writing formed the Church, which since then is pillar and ground of truth. The Church explains doctrines and applies them to the new times, but she does not depart from the Sacred Deposit of Faith "once delivered to the saints".