Add an additional column to the gradebook which displays the report card grade.   Give the option under gradebook settings to display or not display this column.   During end-of-term, the teacher doesn't necessarily know or remember that they need to recalc their report card grade (or submit a grade change to request a change to the report card grade).   It just isn't easily visible that there is a difference in the gradebook grade and the report card grade.    It isn't visible on the grading tab either as the gradebook grade that is displayed there is the gradebook grade at the time of calc.