Can multiple TA/TFs comment/annotate the same assignment in the gradebook?

Yes, but you need to be careful. You may be interested in using moderated assignments - see the Canvas guide on How do I add a moderated assignment to be graded by multiple reviewers - Instructure. Moderated grading allows multiple reviewers to grade a students work and create draft or provisional grades for an assignment. For instance, you may want to allow two TAs in your course to grade all assignments, and you can review their assessments before determining the final grade.

If you do not want to use moderated assignments and would like multiple instructors to be able to comment/annotate submissions, then you need to be aware that the SpeedGrader is designed only for one instructor to be grading at one time - you will lose comments/annotations if multiple people are commenting/annotating on the same assignment at the same time. A workaround may be to assign timeslots for graders to prevent overlapping grading.