If you click an email confirmation link to https://en.wikipedia.org/wiki/Special:ConfirmEmail while logged in then you get https://en.wikipedia.org/wiki/MediaWiki:Confirmemail_loggedin:
"Your email address has now been confirmed."
The email gives the username but Special:ConfirmEmail does not. While making email confirmation for PrimeHunter3, I was logged in as PrimeHunter and got a page saying "Your email address has now been confirmed." It's a confusing wording when it does not refer to your logged in account. I suggest Special:ConfirmEmail gives the username in this situation. Something like "The email address for USERNAME has now been confirmed."
If you are not logged in then you get https://en.wikipedia.org/wiki/MediaWiki:Confirmemail_success:
"Your email address has been confirmed. You may now log in and enjoy the wiki."
It would also be OK to always give the username.