I can’t really test this because I’m not using the language plugin anywhere but I might be able to help you figure something out.
What does it not do? What is working?
One of you’re problems may be the print and var dump lines. The rule match happens in a AJAX call and that could be causing the AJAX request to fail. The best way to get information on what’s happening during an AJAX request is to turn on error reporting and logging in WP and then use the PHP function error_log() to write stuff to the error log, then look at the error log to see what the output is.
