Sorry for the delay.
First you need to build an array for the switcher:
$switcher = array(
'urls' => array(
'fr' => false,
'en' => 'https://',
),
'main' => 'fr',
);
Then update the 2 following post meta data:
update_post_meta( $post_id, 'lsw_language_switcher', $switcher);
update_post_meta( $post_id, 'lsw_main_language', $switcher['main']);
If you are editing a post that already has settings don’t forget to merge the previous array with the new one:
$switcher= get_post_meta( $post_id, 'lsw_language_switcher', true);
// add/modify english url
$switcher[urls]['en'] = 'https://';
update_post_meta( $post_id, 'lsw_language_switcher', $switcher);