faulty URL logic in _localizer_redirect_with_language

  foreach ($_GET as $key=>$value) {
    if ($key == 'q') continue;
    if($query) $query .= '&';
    $query .= $key .'='. $value;
  }

You cannot just concat $_GET variables into a query string, they need to be url encoded. This should be something like drupal_query_string_encode($_GET, array('q'))