What do you bet that the words "at Rome" are not in Irenaeus' original autograph but were added by later dishonest Latin translators.
Irenaeus would have known from Paul's Epistle to the Romans that the church in Rome was alive and well before Paul or any apostle had been there. Neither Peter nor Paul founded that church. If Irenaeus was confused on that point, then his credibility in the rest of this paragraph is called into question, that is, if he actually wrote that paragraph at all.
Well, what would be the evidence of such tampering though? We'd have to find other, older manuscript traditions that didn't have those words, and then maybe we could conclude they are not original. I'm not aware that any such MSS exist.
But I think the evidence leans against tampering, because as you can see from the original passage (linked above), there is not just one throwaway reference to Rome but a whole line of Irenaeus's argument. He goes on in the same chapter to enumerate the bishops of Rome after Peter and Paul were there...Linus, Cletus, Clement, and on and on. He basically says that the Apostles appointed people in a direct line right down to the catholic Church (and yes he uses those words) of his day.
So if this reference to Rome is forged, then it's not just a matter of two words.