I'm absolutely the last person to be talking about this, but no, you shouldn't have to update the paths when you upload to the remote server.
The localroot and remoteroot globals are indeed relative to the site root, but that is (I think) determined by the (__FILE__) (and realpath) functions in the addtosite.php file.
When you use the same globals file on your remote server, it will also create an absolute path based on the realpath + (__FILE__) + global root values, so your include code will turn into something like:
<?php
include('/home/users/ukr86294/html/yoursite.co.uk/CMS/WA_CMS/addtosite.php');
echo WA_getCMSContent($database_localhost, $localhost, 'Home' , 'local_groups');
?>
depending on how your remote server paths are cofigured.
But hopefully an expert will add to that.
