I apologize for the additional post.. My last one expired..

Small change I made the the fileset structure:

I moved this file:
/includes/languages/english/extra_definitions/YOUR_TEMPLATE/events_calendar_include_defines.php

to here:
/includes/languages/english/extra_definitions/events_calendar_include_defines.php

There's no need for an override for this file since this is NOT a default Zen Cart file. Any shopowner who makes changes to this file certainly SHOULD create an override for it, but the Events Calendar fileset doesn't need to put it in a template override folder..