There's actually a very intriguing backstory behind the term
Bowserotti:
as you know,
it's the only Western translation of the old KoKuppa term, no longer in use since the GBA Mario & Luigi: Superstar Saga, that translates Kuppa as Bowser and thus the whole term as Little Bowsers.
Kuppa being Bowser from the start rather than what became the American concept of
Koopas (=the various turtle-like creatures) was only recently acknowledged in the Spanish translation of the Encyclopedia Super Mario Bros., where the
Koopas concept has been completely abandoned in favor of the Japanese
turtle family and
Kuppa is consistently translated as Bowser. As far as North America is concerned, if the Official Home of Mario is an indication,
the Koopas concept is still in full use, but the
reuse of the Super Mario All-Stars Wii story of Super Mario Bros. indicates that they too realized
the mistake they made back then when the
Koopas concept was introduced.
Bowserotti, however, isn't a recent term: it came out
in Super Mario Advance 4, which is why it's a translation of
KoKuppa instead of
KuppaNoTeshita (Bowser's Minions) or
Kuppa7Ninshu (Team of 7 Bowsers), and in that manual it was indeed said that the Little Bowsers were Bowser's children, just like the Japanese
manual and
Nintendo Official Guidebook of that game said (
after the introduction of Bowser Jr.!).
I don't know who did this important correction back then when nobody had apparently spotted the
Kuppa issue yet (I suspect it was
Francesca di Marco, who was involved in the localization of The Legend of Zelda: The Wind Waker, Mario & Luigi: Superstar Saga and Paper Mario: the Thousand-Year Door), anyway, thanks to it in Italy the Koopalings are still known as Little Bowsers, even though Nintendo Italia is now forced to stick with their current depiction.
But why is the term still in use? Nintendo Italia was indeed using since New Super Mario Bros. Wii the
Scagnozzi di Bowser (Bowser's Minions) term, and they used it until Super Smash Bros. for Wii U, but then Japan since Mario Kart 8 started using
Kuppa7Ninshu instead of
KuppaNoTeshita, likely because the latter was too generic, and with Mario & Luigi: Paper Jam Nintendo Italia caught the chance to reuse the old term (
they also made Lemmy call upon his father, by the way...).