A heavy, heavy amount of derivative works building upon/criticizing/amending/defending the massive four volume, eight book 6.000 page biography of Mussolini by Renzo De Felice have been published - for a while the works of De Felice basically defined the study of Italian Fascism. In fact, if a biography of Mussolini or a history of Italian fascism doesn't at least reference De Felice's work it can be considered highly suspect.

Having said that very, very few of his works have ever been fully translated to English. There has never been a complete English translation done of his Mussolini biography, with the most being excerpts in various English language collections and textbooks.

This is part of the reason why I stated that work that doesn't reference De Felice's can be considered suspect because it tends to indicate that the author isn't familiar with the Italian language and needs to rely on other's interpretations and translations.

I've been listening to lots of podcasts and reading accounts of Roman life and battles recently in my free time

In Classics a huge amount of work remains untranslated, particularly in German and French. There's simply no need for it, any good Classics graduate program requires not only advanced competency in Greek and Latin but also reading competency in at least one of the major European languages of classical scholarship (French, German, and Italian). As far as Classics go what you're asking is kind of like asking whether scholarly traditions exist in other countries, to which the obvious answer is yes. Classical scholarship in some languages, like Japanese (believe it or not the Japanese produce a rather high volume of excellent work, if you can read it), remains untranslated for other reasons, mostly that few people have enough knowledge of the subject matter, the classical languages, and the scholar's language simultaneously to be able to reliably translate (with Japanese this is enough of a problem that I've had professors even ask me if I can help them out, since they don't want to pay the rather high rates for translators). But in the case of most classical scholarship it's simply because we're expected to be able to read those languages without much trouble, and translation is expensive and time-consuming.

The single most important primary source of the late Sengoku Japan not written in Japanese is Jesuit Luis Frois' Histories of Japan, a long and detailed work (my Japanese copy is 12 volumes) that provides important insights to the major characters and events of the late Sengoku, written in Portuguese.

And no one has translated it into English.