It was written about, because it did happen.
Peter mentions Rome in his own epistle. He says he is writing "from Babylon", which in Christian parlance referred at that time to Rome and NOT ancient Babylon--that's straight out of Revelations 17.
Then the Fathers. Clement of Rome in around 90 mentions Peter's martyrdom, though not where. Ignatius of Antioch a few years later says to the Romans that he does not "command you as Peter and Paul did". Eusebius cites a letter to Soter written by Dionysius of Corinth (A.D. 170) where he says explictly that Peter and Paul were at Rome. Eusebius also cites a fragment of Gaius's Disputation with Proclus from around A.D. 200) who says that the "trophies" of the Apostles who founded the Church of Rome were at the Vatican and the Ostian Way in Rome. Clement of Alexandria is quoted in Eusebius as saying Peter preached at Rome. Tertullian said explicitly that Peter was in Rome and poured out his doctrine as well as his bloodl this was again around 200
And as for Irenaeus, writing around 180 or so...you call his description of Peter in Rome a "word or two"? How does this description qualify as a "word or two"?
"Matthew also issued among the Hebrews a written Gospel in their own language, while Peter and Paul were evangelizing in Rome and laying the foundation of the Church" (Against Heresies, 3, 1:1 [A.D. 189]).My goodness, he sounds practically ultramontane in his description of the Bishop of Rome!"But since it would be too long to enumerate in such a volume as this the succession of all the churches, we shall confound all those who, in whatever manner, whether through self-satisfaction or vainglory, or through blindness and wicked opinion, assemble other than where it is proper, by pointing out here the succession of the bishops of the greatest and most ancient church known to all, founded and organized at Rome by the two most glorious apostles, Peter and Paul, that church which has the tradition and the faith which comes down to us after having been announced to men by the apostles. With that church [of Rome], because of its superior origin, all the churches must agree, that is, all the faithful in the whole world, and it is in her that the faithful everywhere have maintained the apostolic tradition" (ibid., 3, 3, 2).
"The blessed apostles [Peter and Paul], having founded and built up the church [of Rome], they handed over the office of the episcopate to Linus. Paul makes mention of this Linus in the letter to Timothy [2 Tim. 4:21]. To him succeeded Anacletus, and after him, in the third place from the apostles, Clement was chosen for the episcopate. He had seen the blessed apostles and was acquainted with them. It might be said that he still heard the echoes of the preaching of the apostles and had their traditions before his eyes. And not only he, for there were many still remaining who had been instructed by the apostles. In the time of Clement, no small dissension having arisen among the brethren in Corinth, the church in Rome sent a very strong letter to the Corinthians, exhorting them to peace and renewing their faith. ... To this Clement, Evaristus succeeded . . . and now, in the twelfth place after the apostles, the lot of the episcopate [of Rome] has fallen to Eleutherius. In this order, and by the teaching of the apostles handed down in the Church, the preaching of the truth has come down to us" (ibid., 3, 3, 3).
This is the extent of the evidence of Peter being in Rome. They knew nothing more than that??? The "Prince of the Apostles" warrants an occasional mention of which even these writers are unsure about their statements of his presence there. He leaves no footprints, no monuments, no church named after him, no decrees, no relics, and no bones ---- just claims that turn out later to be unverifiable.
And as for Irenaeus, writing around 180 or so...you call his description of Peter in Rome a "word or two"? How does this description qualify as a "word or two"? "Matthew also issued among the Hebrews a written Gospel in their own language, while Peter and Paul were evangelizing in Rome and laying the foundation of the Church" (Against Heresies, 3, 1:1 [A.D. 189]).
Irenaeus is incorrect here. Paul's letter to the Romans demonstrates that for the church of Rome was founded and established before Paul had even visited it as he wrote in his letter circa 56AD. Irenaeus gets several of his facts wrong, but even he admits that in cases like this one should defer to the scriptures and ignore his statements.
He says that Paul and Peter did this together and yet history has Paul in prison during most of his entire Roman sojourn with no time for evangelizing. And when he was out of prison, tradition says that Paul travelled to Spain. So just when could Peter and Paul have been evangelizing together????
Ask your magisterium how much of what you quoted from Irenaeus is accepted by them to be true.