Thanks for the details!
I checked your site and seems you are facing cs-vendor.js loading issue. which is required to run cornerstone.
Contact your host to increase your allocated memory or do it yourself by adding this code in your wp-config.php
define( 'WP_MEMORY_LIMIT', '256M' );
define( 'WP_MAX_MEMORY_LIMIT', '512M' );
If that doesn't help please delete theme and cornerstone and re-upload a fresh copy of the theme.
Let us know if that works.