Adding Polylang to frontend admin bar

Hello,
I am trying to add Polylang language switcher on front-end admin bar (or toolbar). I added the necessary code on wp-includes/class-wp-admin-bar.php and it works but apparently, it is not advised to change those files (belonging to WordPress core), even on child-theme. So I tried to add this code line with “$wp_admin_bar” but it does not work.
Do you have any idea on how it is possible to add this switcher on front-end admin bar (not back-end)?
Thanks.