First of all, you are using an old version of the theme which is not compatible with Cornerstone version 3.0.4. Please back up your website completely and update the theme to version 6.0.4.
Secondly, I am not sure how you added the shortcode. If you use the Cornerstone please use the Classic Raw Content element to add the shortcode.
And finally, I don't think the shortcode rendering is something related to our theme. Please add a test page and simply add the shortcode of the plugin inside the standard WordPress editor and change the theme from X to one of the default themes of the WordPress and check the case. If you still have the problem then you need to contact the plugin developer to get help as it is not related to our theme.