Currently, with the new Gradebook, there is the Final Grade Override option. For all columns, other than Final Grade Override in Grades that receive a score (Assignments, Quizzes, Discussions), there is an entry in Gradebook History which indicates who and when the entry/change was made. The Final Grade Override column does not create an entry in history when a value is entered or changed.
Having an audit trail for all changes made to any grades in the Grades tool is important not only for accountability, but also to track down an potential errors in grade entry - especially when a course may have multiple individuals capable of making grade changes for a student.
Adding the Final Grade Override column as an entry in Gradebook History will bring consistency and needed auditing to the new grade book.