Most grading activity can be done in Speedgrader (reading submissions, scoring, making comments, using rubrics) but to add missing and late labels the teacher needs to return to the gradebook and use the grade detail tray were they can update statuses, add scores and comments but can't read submissions or utilize rubrics. Having to go back and forth between 2 different tools to complete their grading is a pretty clunky workflow for teachers, but I've been under the impression that we don't see the statuses in Speedgrader because not all institutions are using the new gradebook. With the recent announcement that all institutions will move to the new gradebook in January 2020, is this feature something we can expect to see once the transition is complete?
SpeedGrader is a separate feature from the Gradebook, so functionality has to be developed separately. I do see that others have already created and voted on a related feature idea where you may want to contribute: https://community.canvaslms.com/ideas/13319-apply-status-while-in-speedgrader. That way our product team knows that you would like to see resources prioritized for SpeedGrader to enhance the Gradebook functionality.