As I was explaining in the topic linked by Destroyed, from my point of view, a manual provides added value if it offers an additional perspective on the pedagogical level.
Given that no book can replace direct contact with instrumentalists to truly know instruments well—a means through which pages and pages of books can be replaced in just a few minutes... it is always good to compare multiple texts to best understand, at least on paper, the various possibilities offered by the instruments.
I find Adler more complex than deficient; for knowledge of instruments, I think Piston: Orchestration is very useful... but it is insufficient.
One can do direct in-depth studies on families of instruments or single instruments; see Facchin for percussion (previews available on Google Books) or books like "Extended Techniques for the horn" for the horn, etc.
However, a composer needs to understand how to manage these potentials, and an excellent text is Kent Wheeler Kennan, which is specifically designed to develop this ability. It practically takes for granted that you already know the instruments and focuses on textures—something that is always neglected; it starts from examples and proposes possible orchestrations, all balanced and functional in both pp and ff.
To enrich the discussion, you will have appreciated Leibowitz, which you sent to Gozzo in PDF format at the time. It is practical and very interesting due to the commentary and the ultimate proof with original works (among them significant fragments... where the orchestration of the 'Frank' in question will surely be different from that of the 'Genius' in question).
But not because only one version exists or because one hasn't reached it, but because among the various possibilities that might come to mind (even the most original ones), you then discover that you have "more" to learn.
It is interesting to understand what drove, for example, Beethoven to use solution X rather than Y, etc.
Coming to the question of the topic, namely manuals in Italian. I would look for a text as an alternative to these only if it provided different points of view on the matter; it is better to replace Mortari with Piston; Leibowitz is already in Italian; I don't think Kent Wheeler Kennan has ever been translated. I am not familiar with Cusatelli, so I ask AleGozzo to post at least the index... from this, many things can be understood...
If it were a duplicate of the other three in terms of pedagogical approach, why should I buy it? The only answer that comes to mind is for a strict linguistic problem, regarding translation... otherwise...? ...
If it were an in-depth study from a historical perspective, perhaps there would be other examples, so it might be worth it... Ale...?
Clearly, I have the PDFs of the three manuals I mentioned, so:
Piston's Orchestration
Kent Wheeler Kennan
Leibowitz
If you need anything, PM me with your email address