For one of my courses, I have 29 teaching assistants who are grading papers online within Canvas. Each student's paper is graded by at least 2 teaching assistants.
Here are my issues/suggestions.
1. Allow the system to calculate a mean score based on the graders scoring using the grading rubric for a specific assignment.
2. Allow all graders comments and annotations to be viewable by the student. Why? I teach in a professional pharmacy program and I want my students to realize that everyone reads a paper differently, even with a rubric and receive all of the feedback. This is similar to what happens when we receive feedback on a manuscript submitted to a journal.
For my last manuscript submission, I had 6 reviewers and all of their comments were sent to me in a single document with a summary of accept, accept with revisions (major or minor), or reject. Canvas should be able to do this as well.