I recently noticed someone applied a minor edit to one of my answers that changes a word from British English to American English. I searched around a bit, and found similar questions on other SE meta sites. The first relates to asking questions, and the second to adding tags. I am just curious if UX SE has a "preferred language" for consistency?
There is no official version of English, aside from StackExchange being an English Language site.
It is possible that when questions / answers written in one country are edited by someone in another country their own browser spellchecker will highlight words as incorrectly spelt when infact they are just spelt according to the original posters language. Perhaps this is the situation here? (I don't know the actual post you are referring to to be able to confirm).
We wouldn't encourage editing posts just to change from US to UK (or vice-versa), and if a suggested edit came up for authorisation that only included such a change it should be rejected as 'Too Minor'.
I stumbled across an answer that seems to draw a clear distinction between body text (doesn't matter) and tag text (only American English). That came from the accepted answer. The most-upvoted answer says "it should not matter, so do not edit". It is from SE Meta though.