Cool, thanks for the update! Heh, don't believe all you hear
Studio Musicale Romano seems to have been active as a publisher already in the 1920's, so I don't see it as very likely that it was founded by Sandro Brugnolini.
You have this box set, right? Are there any dates on there, in the runouts perhaps?
As for other releases, I found some 7-inches and I think there are some classical music recordings as well. As for these FS library releases, I don't know of any other... yet.