I'll check my Chilean books (and Latin American more generally) when I get home. I know all of my French-language books are written that way so it's possible it's a French influence or some common shared influence
I was about to say, my (two?) French books are also reversed. (I own two different editions of Le mariage de Figaro)
I work at a library in California that has Spanish, Russian and Ukrainian in addition to English. I have a picture I took the other day of a shelf of Ukrainian, and they're mostly bottom-top. The top-bottoms all seem to be translated to Ukrainian, but there are other translated works that go bottom-top. I don't work again until later this week but I will report more findings when I do!
PL/EN – https://lfs.nabijaczleweli.xyz/0015-cohost-images (2023-01-23-tsiro…); I'd say that older polish books (the lenin tomes, lem, pitaval krakowski, it's a relatively old edition of szatan z 7 klasy IIRC and hiperprzestrzeń) are the only ones that go up. newer books and all the english ones go down (some older ones do as well, those are my parents' chemistry textbooks)
a 1985 russian dixionary goes up (cyrillic, russian-published), a modern one goes down (latin, polish-published); a modern ukrainian book goes down; the second batch ibid. (0351-0353) mostly mirrors this trend – Modelarstwo okrętowe and Człowiek zdobywa głębiny are printed 1985 and 1984, resp.; the three oddballs here are the Turbo Vision book – 1994, the only computer-related book going up – сила привычки (2014 ed., but the publisher e-mail is @gmail.com, so.), and the fulghum book from 2009, but I also don't recognise the publisher, so.
Swedish books are the normal, red-blooded and God-fearing orientation
I have a few books published in English but on the Continent—or 'in continental Europe', to put it less parochially—with bottom-to-top spine labelling, which are interesting but not unexpected.
The real curiosity I have on my shelves is a book published in English in the UK with bottom-to-top spine labelling: Michael Benskin and M. L. Samuels, eds, So meny people longages and tonges: Philological Essays in Scots and Mediaeval English Presented to Angus McIntosh (Edinburgh, 1981). Why? Well, I don't know, but some possible reasons are
My guess is a combination of (1) and (3).