User blog comment:Sarah Manley/Updates to Wikia Chat/@comment-1649337-20120509141928/@comment-1613840-20120509164055

Hi, they actually are MediaWiki messages:

'chat-user-was-banned' => '$1 has been banned by $2 $3.' 'chat-you-were-banned' => 'You have been banned by $1.'

If you have further issues finding them, please let me know.