I have that book too, a golden resource if you ask me. The rounded bridges were on the two built by the yard in Fiume, 'Fulmine' and 'Baleno'. Also, 'Dardo' and 'Strale' had straight stems while the rest had the arched stem you see on my model.
While we're talking details, I should bring up the major problem with the plans. Now I love Profile Morskie both for their incredible draftsmanship and their affordability, but everyone makes a mistake at some point. The plans show the anchor hawse holes on the bow, and that's how I built it. However, in M. Brescia's book, he points out that all of the class had their anchors relocated to the edge of the foredeck in the late 1930s. Several of the pictures show the progression, as more and more of the class were modified, but for sure by 1942 she did not have hawsepipes. The final nail in the coffin is a screenshot I found from a book on RN camouflage in WW2 (that I will probably end up buying) that shows 'Saetta' riding at anchor with the chain clearly coming off the deck edge. Oh darn. Had I known this prior to finishing the hull, I would've tried something, but it's too late now and as they say, 'close enough for government work'.