I'm currently transcribing the following song (I have the text and am getting some help from Italian.SE, as I don't speak Italian!):
The singing is pretty rubato, in particular words often seem to "run-into-each-other", most noticeably when one word ends with a vowel and another starts with one. For example, in this line:
sono assetato e cerco una fontana.
each of the words ending in "o" runs into the vowel at the beginning of the next word, effectively "sounding" like a single syllable.
Would it be appropriate to assign both vowels to a single note in sheet music, in this case, either in Italian or any other language? (Particularly when these vowels are not in the same word.)