You're just discrediting yourself here. You found an uncited footnote in Lataster and conclude that you now know all about it. For now, I will continue not to provide any citations, just because I find it funny to see you flap around like this and want to know how deep a hole you want to dig for yourself.
In addition to the evidence of the textual modification in Galatians 2:1, removing "again," there is the internal evidence here:
Galatians 1:1 - "Paul, an apostle—sent not from men nor by a man, but by Jesus Christ and God the Father"
Galatians 1:11-12 - "I want you to know, brothers and sisters, that the gospel I preached is not of human origin. I did not receive it from any man, nor was I taught it; rather, I received it by revelation from Jesus Christ."
Galatians 1:15-24
In the text of Galatians, we learn that Paul prided himself on having a gospel that he did not receive from any man. In the text of Galatians, we also learn that Paul says that he was unknown to the churches of Judea, and we learn that Paul says that he did not go up to Jerusalem to see those who were apostles before he was, since he received the gospel from a revelation from Jesus Christ and did not "consult any human being." When Paul does meet them, after fourteen years, it was "because of a revelation that I went up." And it is at this time that Paul "submitted to them the gospel which I preach among the Gentiles." At this time, during this meeting after fourteen years, "those who were of repute contributed nothing to me."
And so we have this text:
But, of course, it is a lie. Paul already said that he didn't consult with any human being and that he did not go up to Jerusalem to see those who were apostles before he was. Paul went on to emphasize that he compared notes ("submitted to them the gospel which I preach among the Gentiles") with Peter and James after fourteen years and that they had nothing to add to Paul's gospel. Paul decided to go to Jerusalem at all only after receiving a revelation indicating that he should do so.
All of Paul's statements are trivialized by this interpolation. Since Paul could already compare notes after three years with Peter and James, it becomes meaningless to say that Paul's message was complete after meeting with them after fourteen years. That statement is empty unless Paul was, as he said, someone who had not consulted with the apostles before him, prior to that meeting after fourteen years. And unless Paul was meeting with them for the first time and was uncertain about whether their message would match Paul's, there would be no reason for there to be "fear that somehow I might be running, or had run, in vain" when submitting unto them his gospel to the Gentiles.
It doesn't get much more clear than that. Galatians 1:18-20 is probably an interpolation.
You would need evidence that Paul's letters were insanely popular and widely distributed around the Roman empire in the early second century, to support the claims you were making:"You still have provided no evidence for your beliefs about the transmission of Paul's letters."
What evidence do I need
Paul's letters were insanely popular and distributed across the whole of the geography of Christianity very quickly