Thank you so much for sending me all the information I requested and for being patient. There is nothing in Foreign Language guidelines for this so we go to Formats. It's a little know fact that Foreign Language is actually a subset of Formats anyway. But I digress.
See Formats 21.4.1 and under that Example 21-8 specifically. From the information you've provided, I think these underdots are about pronunciation, but not really about stress or accented vowels because, as you explain, they denote words that are NOT accented. So, that's about pronunciation, but not about accents or emphasis.
I recommend the diacritic underdot. Just list it and identify it as the underdot and perhaps state that it precedes the affected letter. Don't say anything further because the text explains the rest. It does not appear that the dots assignment 35 conflicts with any of the Italian special symbols.