This idea has been developed and deployed to Canvas
When exporting grades in the new gradebook, the entire course (all grading periods) are exported. Because of this, the "current grade" and "final grade" columns from the CSV file do not match the "total grade" column from the Canvas gradebook. Instead, the CSV is combining all grading periods together for a full calculation. This functionality was available with the old gradebook, but got lost in the new gradebook. This is essential!! Please, please allow teachers to export their gradebooks by grading period.