Hey @edebex,
Thanks for reaching out to us! I’ll help you here, but first let me say that editing the language file (.po) is not recommended as your changes will be overwritten with plugin updates. There’s a really handy plugin to do this safely: Say What?.
Now regarding the string for Free not translating there, I’m not sure why that happens. If you decide to use the above mentioned plugin it might work, if not you can use the followin snippet (just paste it in your theme (or child theme) functions.php file):
/*
* Change the Free ticket label
*/
function change_free_label ( $cost, $post_id, $with_currency_symbol ) {
if ( $cost == 0 || $cost == "" || $cost == "Free" ) return 'gratuit';
}
add_filter('tribe_get_cost', 'change_free_label', 20, 3);
Please let me knows if any of those solutions work for you,
Best,
Nico