Translation .po file

Hi. I translated all the missing string into the Italian .po file. I uploaded into the folder wp-content/languages/plugin and it works correctly. But after short time (hours?) it reverts and the important strings are missing again.

Example string such as “Lost password” etc.

How to have translation via .po file to be used permanently?

I already contribute to the public translation but my translated string still stuck into “waiting” status. Actually, it’s the same as there is no Editor for the Italian version.

Thank you.