I\'ve re-installed WAMP multiple times, searched literally hundreds of pages, and its not fixed this issue:
$cfg['Lang'] = 'en-utf-8'; and friends change the language for phpmysql, not for the mysql server, so anything coming from the database server itself will be unaffected.
You need to start the server daemon with --lc_messages=en_US (or put that in the relevant config file), for a per-session setting just use SET lc_messages = 'en_US';