Hi there,
Thanks for writing back. You always need to keep the parent theme (X) updated and don’t need to update Child Theme since it contains your changes. Updating Child Theme will override the changes you made so far.
You are not using the latest version of X or Cornerstone. Also you have X Shortcodes installed that you need to remove as it’s replaced by Cornerstone.
You can find the latest version numbers here: (http://theme.co/changelog/) Then you can compare them to what’s installed on your site.
If you find anything to be out of date, you can review our update guide.