Hi,
K2 v 2.9.0 with italian language, all works fine, the only thing that is not translated is flatpickr calendar in backend like you can see in attachment image.

How can I translate moths and weeks in Italian language?

Thanks in advance

What translate method you refer?

The transations methods not work with that calendare because is an external calendar.

I solved useing this method if anyone need to know too:

components/com_k2/helpers/html.php

row 197 added cdn:
$document->addScript('cdnjs.cloudflare.com/ajax/libs/flatpickr/4.6.3/l10n/it.js');

media/k2/assets/js/k2.backend.js
row 738 added:
time_24hr: true,
locale: 'it'

I understand, thanks.