System blocks me, and I will make direct change at software.
EDIT: I done this https://gerrit.wikimedia.org/r/#/c/mediawiki/core/+/490698/ and after deployment of this patch, everything should be fixed.
According to the comment by Thiemo Kreuz (WMDE) in gerrit it seems we can't change it there and we have to do it here. I've tried contacting an admin, let's see if it's possible to fix it.
I have updated the translation and changed the AbuseFilter rule to allow this for translation admins.
I noticed this was declined in gerrit, so I have reverted my change for now.
@Nike: Could you please restore your change? As I wrote before, there is no project that uses that name for its main page. There are not pages that would be influenced, both Wikipedia and the Wiktionary used "Pàgina printzipale". On gerrit the patch was declined because "The existing name is nearly 10 years old now" but it's a wrong name that was never used. I would like to create the Main pages for Commons and Wikispecies, but the name for those should be the same as the Wikipedia one so for now I still have not done it.