During workouts; adding a "comment/ note" sections after each exercise
When my clients and myself are using Trainerize I explain it as a "digital journal". I think it would be beneficial to add a "notes" or "comments" section after each exercise. For instance if I complete a Bent Over Row and my 3rd set was too light at the bottom of that exercise I could make a note i.e "go heavier next week on 3rd set too light". It could be as easy as where it usually says "+ ADD NEW SET" there could be another option saying "+ADD COMMENT".