Hi, on the KSP wiki I'm unable to get the translated language. I created an example where both text's show it in Arabic and not in English or German. The MediaWiki version is 1.21.1 (according to Help:Magic words it was added in 1.18), PHP is on version 5.3.21 (cgi-fcgi) and MySQL is on version 5.1.70-cll.
Topic on Project:Support desk
Apparently, it requires the Extension:CLDR installed for the second parameter to work. I'm going to clarify that on the Magic words help page now.