Hello,
after the latest update the "Add Yours" text (top of the comments list under joomla article) does not seem to be associated with a language string anymore.
At least, I have this string in my italian language file
COM_KOMENTO_COMMENTS_ADD_YOURS="Aggiungi il tuo"
but I still see the text in english
With a quick check I wasnt' able to find the file generating that text, so I leave it to you...