The Italian text says "Questo utente" (masculine form of the adjective) for "This user" regardless of the user's gender, but if a user's gender is set to female it should say "Questa utente" (feminine form of the adjective), since "utente" can be masculine or feminine depending on the gender of the person it refers to (see en:wikt:utente). However, since "utente" begins with a vowel, it would also be correct to say "Quest'utente", avoiding the question of gender entirely, so I recommend changing the text to use this neutral form.
Topic on Extension talk:Babel
Thank you very much @CalendulaAsteraceae for speaking up about this problem. It's been a year, yet the text still uses the masculine form only. The Spanish template already changes based on the user's gender, which shows that the change is possible.
And thank you for reminding me of this issue! I've filed a bug report at task T365928.
@Dream Indigo: By filing this bug report, I learned that translations are handled through Translatewiki.net, which is mentioned on the main page but not very prominently. I have now fixed this issue on Translatewiki (e.g. translatewiki:User:CalendulaAsteraceae), and hopefully we'll see that change propagate here soon. If you spot any other issues with Italian translations, feel free to let me know!
Thank you so much @CalendulaAsteraceae! I am so happy that you solved the issue! Luckily, I haven't found any other problem so far. I have already fixed every other male-only userbox on it-wiki some months ago, but I needed the help of an expert like you to solve the Babel issue. Thanks again! I am really happy!
New code, including translations, is deployed weekly between Tuesday and Thursday, with most Wikipedias getting it on Thursday. Unfortunately you missed the Week of May 26-31 deployment so your change should roll out with the Week of June 3-7 deployment.
@Pppery Thank you for letting us know, we'll be waiting patiently :)