It would be best to keep your Wordpress version update since the updates we release on our end adheres to the Wordpress standards.
Also, the latest update for X and Cornerstone only supports Wordpress version 5.0 and newer version of Wordpress.
Another key thing you need to make sure of is that when you update X or Cornerstone, you have to update both of them because it will cause an incompatibility issue if only one of them is updated.
Lastly, please also make sure to fully clear your site and browser cache to make sure that you are seeing the latest version of the site.
It is a good practice to do all the updates on a staging site first to make sure that in case there are some issue with the update, the live site will not be affected.
Hope this helps.