Your opinion of Paul is far too small. It was his knowledge of the Old Testament that allowed him to explain the transition from the old covenant to the new covenant because it was there all along. It was merely concealed.
And confirmation isn't teaching someone. It's merely reinforcing what they already knew and professed. Peter did not have superior understanding than Paul. This is easily discernable by merely reading what each wrote.
I am a natural born Jew who had similar training Paul did as a boy in the Torah and Scriptures + Talmud in Synagogue. I understand him perfectly. Definitely better than the Reformed.
So let's put this onto you then.
You didn't know what Jesus said until you read His words and saw the Disciple use the same terminology that "confirmed" the words of Jesus.
What did Jesus say to them?
1. 47 and that repentance for the forgiveness of sins should be proclaimed in his name to all nations, beginning from Jerusalem.
2. 16 Whoever believes and is baptized will be saved, but whoever does not believe will be condemned.
3. 38 Whoever believes in me, as the Scripture has said, ‘Out of his heart will flow rivers of living water.’”
39 Now this he said about the Spirit, whom those who believed in him were to receive
So Jesus said to His Disciples 1. Repent, 2. be Baptized, 3. receive the Holy Spirit
How did the Disciples confirm what Jesus said?
Peter confirmed Jesus Words:
38 And Peter said to them, “Repent and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins, and you will receive the gift of the Holy Spirit.