Is there a way for the initiator to see what Additional Pay has been submitted?

Yes. There are multiple pages that will allow you to review Additional Pay that has been submitted and approved.

1. Payroll Tasks Tile > Payroll Transactions > Self-Service Transaction Links > Approve Additional Pay (E-330)
2. HR Tasks Tile > PayPath/Additional Pay > PayPath Actions > Additional Pay Tab
3. HR Tasks Tile > PayPath/Additional Pay > Create Additional Pay