I don't see Paul appointing Bishops here, does your "tradition" tell you that this is what he is doing? I see Paul instructing what the qualities in the individual should be. The actual selection was determined by the congregation in the early church.
The top down hierarchy developed later.
The only Apostle who might be considered a Bishop is James, the brother of Jesus, but if you read Acts 15 you will see that decisions involved the entire congregation.
Perhaps a "top-down" heirarchy was there all along, just not addressed in terms we use today.
Catholics are not congregationalists because they do not believe that authority rests in the congregation. They believe it rests in the hierachial model. In this model, authority must be held accountable. If it fails, then authority will pay the price. It is a paradigm, if you will, based on sherperding and not on sheep. References to shepherding as accountability can be found in Jeremiah and Ezekial, just two Biblical of a number of Biblical examples.
I am not in any way an intellectual with debating skills--these were not in God's life plan for me. But I do have faith and it rests in Christ Jesus and the Church He founded and that Church does not derive its authority from the congregation. If that were so, the congregation would be accountable for the authority and not the other (proper) way around.
The accounting must stop at some point at the top.
This passage is not about Paul appointing bishops, per se, but that they were there in the early Church.
Matthew 28:18-20
"And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth. Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you always, even unto the end of the world. Amen."
The Apostles went to all nations: James the Greater to Spain, Thomas to India, etc. They appointed bishops to succeed them, especially since they (the Apostles) were all martyred within a relatively short time. (There are articles on-line which explain which Apostles went where and how they were martyred.) The only one who was not was St. John, who had been exiled to the island of Patmos and lived to be quite elderly.
The bottom line is that there are historical documents out there which describe the Early Church in detail. You just have to be willing to research.
how sad for the churches st paul founded since they could not kniw 'everything' as you out it since scripture wasn't even written yet.