So you want this code: <?php echo ucwords(preg_replace("~^(.*?)\..*$~", "$1", $_SERVER[HTTP_HOST])); ?> to output region name and not slug?
Use this then:
<?php echo Region::newInstance()->findBySlug(ucwords(preg_replace("~^(.*?)\..*$~", "$1", $_SERVER[HTTP_HOST])))['s_name']; ?>
It will search for the region by its slug and output its name.
Regards.