These are terribly obscure, unfortunately. Never heard them, nor seen them for sale.
In addition to the Renosto cues, there are some works by A. Riccardo Luciani, "Gisteri", "Raskovich" and "Winkell" on these LPs that I'd very much like to hear.
Reissues? Not that I know of. Not yet, at least.
Like the similar (possibly related?*) Edizioni Leonardi, Nazionalmusic is still operating as a publishing company in Milano, as far as I'm aware. Maybe if someone were to get in touch with director Floriana Bozzalla, we could get a digital reissue somewhere down the line?
edit:
* It isn't necessarily relevant, but interestingly, their business address is currently the same as Leonardi's; Corso Europa 5.