Thank you for your reply
Well, I have translated minimatica in this manner:
1) I opened minimatica.pot in the /languages directory with poedit
2) I saved the file in poedit as it_IT.po and it_IT.mo
3) I translated all sentencies with poedit
4) as soon as I completed the translation, I saved again it_IT.po and it_IT.mo, and I copied them into the /languages directory in the minimatica theme directory
5) finally, all translations work well 🙂 expect the one marked in the starting post (comments.php row 67)… is there something wrong??
Thank you again