Its an old thread but thanks @Long Nguyen. I found a solution that works for me. I am sharing a snippet (inserted on admin_init) below in case anyone else is interested.
<?php
$value_title = rwmb_meta( 'custom_field_site_title', [ 'object_type' => 'setting' ], 'site-options' );
$value_tag = rwmb_meta( 'custom_field_tagline', [ 'object_type' => 'setting' ], 'site-options' );
update_option('blogname', $value_title);
update_option('blogdescription', $value_tag);
The snippet updates the options in database whenever the custom fields on the Settings Page are edited.
Kind regards,
.
