In apartment buildings, where dozens of families share one large basement room to store things like Christmas trees and off-season air conditioners, it’s called the “storage room”. NY and Boston area.
If I read “box room” in a book that took place in the US, I’d find it a bit odd but understand what you meant by it. The part about taking place in the US is important, though, because we expect books placed here to sound like they’re really here. In the case of a book merely aimed towards capturing an American audience too, I don’t see an urgent need to switch things around…unless it’s the unusual instance of the narrator being “American” and needing to sound it depite the story being set in the UK.
It depends on what you read, really. Kids’ books seem to be changed a lot more often than books meant for adults, and the more popular the adult novel the more likely they feel the need to change those too. Try “The Breaker” by Minette Walters some time. There are a lot of Britishisms in it that haven’t been changed for us.
As has already been mentioned, they generally only change children’s books. Whether that’s a good idea or not is debatable. Adult books tend not to be altered, except maybe to drop "u"s. Or not. I don’t know, maybe it depends on the writer/publisher. I’m a big fan of Salman Rushdie and I can tell you that the American publications of his books are identical to the British (well, with different covers).
So there are more cases of “double Oh” in US numbers than I would have thought (as I say, I’ve never heard them).
Are there are cases of numbers other than zero being “doubled” in the US? This has always struck me as a Britishism, because I haven’t heard it in the US. And all the examples so far involve “00”.
I’ve always felt insulted that publishers think they have to “dumb it down” for us. “Sorceror’s Stone” has completely different connotations from “Philosopher’s Stone”, which is a term of long standing. And one that I have known about since I was ten or so.
And there are several companies that don’t “translate” for Americans. Penguin never has, so I’ve been treated to colour, flavour, centimetre, connexion, and (in Shaw’s volumes) shew. The editions of Asterix aren’t edited for US consumption, either, and are consequently filled with jokes that require knowledge about British customs to understand. Every now and then I’ll find something out that makes an obscure reference in Asterix make sense.
I just read a non-fiction book about a 19th-century murder that made a number of references to the house’s “lumber rooms” with no explanation of what those were. Apparently they were just storage rooms for whatever, luggage and trunks, etc., not necessarily “lumber.” Who has piles of lumber?
Anyone who heats their house with a wood-burning stove.
That’s a semantics thing, then: I wouldn’t think of “lumber” as wood that is used for anything other than construction.
An extra bedroom with it’s own bath, by the kitchen away from the other bedrooms, is often called a maid’s room. For sale houses will be described as 3br + maid’s, when they are technically 4 bedroom. Never heard of the box room.