I don’t know that it’s necessarily a standard practice, but these sorts of things are at the least not uncommon. In the 1990s, when the typesetting of ﬁ and ﬂ a ligatures was often done by means of a search and replace, it was not uncommon to look in computer books and see in a block of monospaced text, things like
ﬁle. Similarly, " might appear rather than “ at the beginning of a paragraph because of find-and-replace failures (still common is the use of ‘ rather than ’ for a leading apostrophe in things like ‘76 or ‘tis).
Anyone who reads sufficiently widely will have a collection of proofreading/copyediting errors in their reading experience (another one that leaps out in my memory is in Leopoldo Durán’s memoir of his friendship with Graham Greene where a cut-and-paste mishap led to about a page and a half of text appearing twice in the opening chapter).
Traditionally, there wouldn’t be any sort of localization of texts as they were transplanted from one English-speaking country to another. It would be a bit odd to see, e.g., “colour” in a Faulkner novel or “behavior” in Dickens. That said, as an American author who’s had a few pieces reach first publication outside the US (one in the UK, one in New Zealand and a few in Australia), in those instances, the British-style spelling was applied to the text where there were differences. I also have one piece published in the US which uses British-style spelling, but that’s partly because it is written using KJV-style grammar and the spelling was part and parcel of that.¹
In the case of Pike, as she’s writing for a young-adult audience, I can see there being some desire to avoid the American use of pants as it would be likely to cause sniggers on the part of UK readers, much as, with the first Harry Potter book where the central artifact was renamed to sorcerer’s stone from philosopher’s stone, largely as a result of the US publisher assuming that American readers might be put off by the word “philosopher.”
- I did get a query from the editor about one “you” amongst the “thou”s and I had to point out that it was intentional as that was a second-person plural pronoun.