We've heard from instructors that the Comment Library in SpeedGrader is not very useful because it only allows them to add one comment, total, and because it can only be it to the general comments box, as opposed to adding it to an area within the DocViewer. This is how it currently works in both the legacy and in the upgraded SpeedGrader.
Comment Library in upgraded SpeedGrader
We'd like to request and advocate for a more useful version of the Comment Library that would allow multiple comments that can be dragged and dropped into the student submission, similar to how Quickmarks works in the Turnitin Similarity Report:
Comment Library in Turnitin Quickmarks