Fix and approve, or send back
If the problems are small and you can fix all of them with confidence within your time, fix them yourself and approve. Send the task back only when the problems are big.
When you fix something yourself
Keep the draft IDs. Use new_1, new_2 and so on for added rows. Update the change log of every row you edit so it describes your change. Add one line to the overall edit rationale saying what you fixed in review, for example "Review: split c2, removed the overlap between c1 and p1, added new_3 for the user's version limit." Score the fellow's submission as it was before your edits. Then re-run the reviewer checklist on the whole rubric before you approve, because one fix can create an overlap elsewhere.