Currently, the "at" keyword in the schedule.ccl file is supposed to report an error if one is scheduling in a group that is not present at startup. It detects this with a regexp, but the regexp does not include boundaries. As such cctk_startupxxx is considered valid.
In addition, the new parser is failing to report a CST error for this violation regardless of group name.
The attached patch to the schedule parser fixes both defects.