The phrase "may have confirmed" is correct and usable in written English.
You can use it when expressing uncertainty or possibility about something that has already taken place. For example: The emails we found may have confirmed the identity of the suspect.
That result may have confirmed an Australian theory.
(His seven years at the Royal Danish troupe, with its treasury of nineteenth-century ballets, may have confirmed him in this loyalty).
An unidentified fighter in Misurata may have confirmed this version of the events to al-Jazeera, saying that he had taken part in the operation against Gaddafi.
It may have confirmed the emotional toll of broken homes, but it said nothing much about growing up with gay parents.
"So the president could be saying something that's in the public domain, but confirming it to the Russians in a way that is very dangerous". In other words, Trump may have confirmed a rumor that was already out there.
(His seven years at the Royal Danish troupe, with its treasury of nineteenth-century ballets, may have confirmed him in this loyalty). But he, too, is rethinking ballet technique.
Bulgarians and Romanians will gain the unrestricted right to live and work in the UK from December 2013, Home Secretary Theresa May has confirmed.
The Senate may not have confirmed Judge Sonia Sotomayor as the newest Supreme Court justice, but Symphony Space and Arturo O'Farrill, the jazz musician, seem confident.
While Noel Fielding may not have confirmed the Boosh are back, he's hinted that he is working with Julian Barratt once more, telling The Nerdist (via NME) they are writing together again.
"If you didn't like West before this, he may well have confirmed all your worst suspicions.
Chelsea's victory over United may not have confirmed that the title race is over this year, but it certainly improved their chances tremendously.
