Is it correct for people to "correct" British English spelling into American English?
I can't see anything in the FAQ about this, and while the site is American in origin, I don't think the British spelling should be treated as mistakes.
We require a consistency in things like tags. In that scenario, I believe our default is American English.
However, when it just comes to one person writing as they write naturally, it is fine to use your own spelling so long as it isn't, well, a misspelling. It's a bit impolite to revise someone's voice if it isn't causing the post to be misunderstood.
I don't think we have a set protocol for this yet.
I propose we follow Wikipedia's standard, which is that as long as a post is internally consistent (either all American or all British), that should be good enough.
Retaining the existing variety
In general, disputes over which English variety to use in an article are strongly discouraged. Such debates rarely accomplish anything apart from wasting time and engendering controversy.
When an English variety's consistent usage has been established in an [post], it is maintained in the absence of consensus to the contrary. With few exceptions (e.g. when a topic has strong national ties or a term/spelling carries less ambiguity), there is no valid reason for such a change.
An article should not be edited or renamed simply to switch from one valid use of English to another. [...]