Link to random post in one specific language

Hi,

I’m trying to add a link to a random post on my site. But this post has to be in the language the user is using at the moment. I found this bit of code and it works, except I cannot force it to stay in one language.

add_action('init','random_add_rewrite');
   function random_add_rewrite() {
       global $wp;
       $wp->add_query_var('random');
       add_rewrite_rule('random/?$', 'index.php?random=1', 'top');
}
add_action('template_redirect','random_template');
  function random_template() {
       if (get_query_var('random') == 1) {
               $posts = get_posts('post_type=post&orderby=rand&numberposts=1');
               foreach($posts as $post) {
                       $link = get_permalink($post);
               }
               wp_redirect($link,307);
               exit;
       }
}

I tried to hardcode the language var here, but it still does not work. And idea where this might go wrong?

$posts = get_posts('post_type=post&orderby=rand&numberposts=1&lang=fr');

https://wordpress.org/plugins/polylang/