We have a fairly freshly installed LAN-based wiki (so I can't link to it from here) which runs on MW 1.27.1. The two first editor buttons (Bold and Italic) show as A A instead of the normal B I like on other EN-language wikis (no biggie, but confusing nonetheless). I assume this is caused by a configuration setting somewhere, but where and what?
Topic on Extension talk:WikiEditor
2 secs later someone figured out that the bar gets confused when there are multiple languages set in localsettings. Removing everything but "en" makes it appear correctly. This really needs to be in the documentation.
"A" is the generic, since the "B for Bold" idea doesn't apply to most languages (it'd be "G for Gras" in French, "F for Fett" in German, etc.).