Shortcode vs

Hi,

I was able to create a shortcode (which is used in an Elementor button) that automatically create a phone text message based on specific custom fields.

Here is the code:

add_shortcode( 'sms_text', 'sms_text' );

function sms_text( $post_id ) {
    $meta_name = rwmb_meta( 'main_contact', '', $post_id );
    $meta_phone = rwmb_meta( 'cellular_phone_number', '', $post_id );
    $meta_custom_message = rwmb_meta( 'custom_text_message', '', $post_id);
    $page_url = get_permalink();

    return 'sms:'.$meta_phone.'?&body=Hey there, it\'s '.$meta_name.'. '.$meta_custom_message.' '.$page_url;
}

Although it is working well, my first idea was to use the "rwmb_{$field_id}_after_save_field" action + the function update_post_meta() to save the value into another custom field...

Unfortunately, I wasn't able to make it work (I don't do much backend coding!). My first question is:
Is using a shortcode a good or bad idea for this purpose?

If yes, what could be the problem in the following code?

add_action( 'rwmb_contact-card-fields_after_save_post', 'sms_text' );

// Get the field value
function sms_text( $post_id ) {
    $meta_name = rwmb_meta( 'main_contact', '', $post_id );
    $meta_phone = rwmb_meta( 'cellular_phone_number', '', $post_id );
    $meta_custom_message = rwmb_meta( 'text_message', '', $post_id);
    $page_url = get_permalink();
    
    $custom_field_to_save_value = rwmb_meta( 'custom_sms_text', '', $post_id); //This is the custom field I want the value to be saved in

    $text_message = 'sms:'.$meta_phone.'?&body=Hey there, it\'s '.$meta_name.'. '.$meta_custom_message.' '.$page_url;
    
    // Preprare update post
    $my_post = array(
        'ID' => $post_id,
        $custom_field_to_save_value => $text_message, 
    );

    wp_update_post( $my_post );
}

Thank you.