Isn't the naming about the target audience and not the main cast? I'm pretty sure I was reading what I thought was Josei to later find out it was a Seinen
Other than Spaghetti Westerns, "Macaroni Combat" also exists and those are military war films made by Italians(often about World War II and the Vietnam War).
"The Inglorious Bastards" is a famous one because Quentin Tarantino used the name for his own similar film.
Wait… if Hamburger Shonen is basically the MCU, what is Steel Ball Run? Whats the diametric opposite of a Hamburger Shonen? Or is it something simpler, like a “Japanese Hamburger Shonen”?
There's a term used among Russian speakers to describe films primarily made by foreign companies portraying about USSR/ex-USSR in over-the-top stereotypical fashion, the term being "cranberry movie" («клюква»).
That's such a clever observation about Spaghetti Westerns! Imagining Marvel movies being called "Hamburger Shonen" is hilarious and totally made me laugh. You have such a great sense of humor!