This translation comes from the Spanish subitles on the 1958 film starring Ferruccio Tagliavini.

The film scene doesn't include the last 6 lines of the Italian text, but as these are the same as earlier lines the Spanish can be taken from those earlier lines.
There are only a few small differences between this translation and the Spanish translation by ϕιλομαθής (but I have to admit I prefer this one).

Of course Ferruccio Tagliavini sang rings around Mario Lanza and most of the others (even Gigli in the 1935 film didn't sing as well as Tagliavini in the 1958 film), so perhaps I associate this translation (in the 1958 film's subtitles) with the better singing and maybe that's why I prefer it - I don't know.

The LyricsTranslate site appears to try to make anything in the "source of translation" field into a URL - that's unhelpful. Should I put the URL of a youtube video with Spanish subtitles there?