Are the style guidelines for sorting absolute, or are exceptions allowable?
The artist sort name for the Welsh band “Los Campesinos!” is “Campesinos!, Los”. Although this follows the style guidelines, it contradicts usual English usage (such as with the US cities Des Moines and Los Angeles). Other sites (Wikipedia, record labels, other style guides) alphabetize using an initial “L” rather than “C”.
Guidelines are not rules 
Edit: to be more specific: if a guideline does not make sense in a specific case, it can and should be ignored - but make sure to point out why you’re ignoring it in any appropriate edit notes. If the situation where it doesn’t make sense is wider than a specific case or two, then it might be worth revisiting it. In this case, if the article is not being used as such, then I’d argue it barely counts for the guideline in the first place, though!
Thanks so much for the reply.
Maybe I’m missing something, but as far as I can see the sort name guidelines don’t say it should be in English - only that it should be in Latin.
Btw, “Los” is even mentioned as an example:
Los Lobos has sort name “Lobos, Los”
PS: Oh, I misunderstood your question I think.
PPS: Generally I think it makes sense for any language to sort articles to the end. For cities it’s different, because you generally don’t use articles when you talk about cities, so if they start with an article it’s an essential part of their name.
The only example I can think of for a band would be Das EFX, but there “Das” is not an article anyway.
Indeed it means Dray and Skoob according to Wikipedia.
But like you, I don’t see why Los Lobos wouldn’t be simply “Lobos, Los” for their sortname.
I don’t see why we should make exceptions when the language is different from their country language.
I mean “The Somethings” band from any non‐English speaking country should still have their sortname as “Somethings, The”.
For better follow‐up, here I copy the Edit #58498508 - Edit artist link and content:
Artist: Los Campesinos!
Sort name:Campesinos!,Los → Los Campesinos!
Yeah I definitely wouldn’t make that a rule either - I’d only make exceptions for certain bands.
E.g. if a band was named “Los Angeles” after the city I’d think it makes sense to sort them “Los Angeles” - independent of whether it’s a band from a Spanish-speaking country.
I would agree with @jesus2099 and @paulakreuzer. I have the group Los Bravos sorted as Bravos, Los. https://www.discogs.com/artist/19787-Los-Bravos.