Early 90's children's book about a girl who travelled back in time has a Community Wiki name which is credited to "Richard". Clicking through reveals Valorum (who, indeed, once used that other name). Why isn't the name updated here?
When a Community Wiki post is created or edited, a copy of the primary author’s username is stored. Therefore, it won’t be changed by that user updating their name (or deleting their account).
Only an edit (even the most trivial) will update the name on these posts.
See also my MSE answer saying the same — but with screenshots!