I generally agree.
My guess, as an American, is that spellings such as "colour" are not as obtrusive or obviously different to American eyes. They'd be more likely to go through, and perhaps even to go unflagged by a spell checker in US mode. I think we have a tendency to adopt British spellings on occasion to add some perceived idea of class or distinction. I'd say I see the British spelling "theatre" at least as often if not more often than the local "theater."
But stuff like "realise," to say nothing of things like "cheque," "kerb," or "tyre," would be a lot more likely to be noticed and therefore to raise the possibility of alteration.
Personally, I'm with you. If there's no policy of what spellings are to be used, it would seem logical to allow each story to use either set, as long as the story was internally consistent.
I get more annoyed when mistakes get actively introduced. I've had apostrophes added to simple plurals, conjunctions removed to leave behind run-on sentences, and other similar mistakes added as well. It's easy to get peevishly upset, in part because the result has my username on it and no one else's, BUT...
As anyone who has ever written, edited, or collaborated on ANYTHING knows, mistakes are an unavoidable part of producing or copying written text. Mistakes can be minimized through care, competence, and perhaps most importantly time, but they will always occur. (In fact, if you study the transmission of manuscripts before the printing press, there is a whole field of study that pertains to analyzing what kinds of mistakes are likely to happen under what sorts of conditions, so that the editors have a good shot at reconstructing the author's original text, since the original manuscripts have crumbled into dust long ago).
It's very easy to feel so protective of one's own work. Which is understandable.
Yes, everything should be consistent and correct every time.
That said, I can't imagine doing the jobs the mods are doing, and I'm incredibly grateful to them. I've learned a good deal from them, and even when they make mistakes, I'd say the balance is heavily in their favor when weighed against my bloopers.
Either spelling is fine. It was probably just that the verifier was using grammarly or similar, or exhausted from late night festive partying/verifying combo.
If it happens, just pm the verifying mod to query. Likewise for any changes you're not happy with.
There are quite a few words that vary from British English to American English. We probably all know about humour and humor. And in Annamique's story it was realise and realize. Realise is correct for her.
Also, there are words that use two l's in British English and just one l in American English.
On the L's"
British - American
cancelled - canceled
cancelling - canceling
levelled - leveled
levelling - leveling
quarrelled - quarreled
quarrelling - quarreling
travelled - traveled
travelling - traveling
libelled - libeled
However, British English and American English agree on these words: annulled, controlled, patrolled, extolled, and enrolled.
It can be a lot to keep up with but we're all doing our best. So if anyone notices that in verifying we've edited a word incorrectly, please let us know. I for one, know I'm fallible. I think that's two l's in fallible, though my spell checker is showing it is incorrect. I'm sticking with two.