Your questions are covered in their e-Notification System manual, which can be found here.
Q71: Is it possible to view notification (contents of notification) submitted using the "e-Notification System"?
A: Though you can view the history of notifications submitted in the past in the "届出状況参照画面 (View Notification Status screen)", you cannot view the detail contents of information you submitted. Please save the contents of notification for confirmation by printing the confirmation screen displayed after entering notification or saving a hard copy.
You cannot check your notification details, at least not via the e-Notification System.
Q73: Is it possible to change the information submitted using the "e-Notification System"?
A: No, once it is submitted, you cannot change the information of the notification. When you find errors in entry or contents in the notification you submitted, re-submit a new notification after entering correct information. If you submitted exactly the same notification multiple
times in one day, only the last notification will be valid.
Q74: I realized that I submitted a notification with incorrect information. Can I change the information? Also, after submitting a notification, can I cancel the notification?
A: When you find errors in entry or contents in the notification you submitted, re-submit a new notification after entering correct information. If you want to cancel the notification, you need to contact the Help Desk of the “e-Notification System”, because you cannot cancel your notification using the "e-Notification System". The Help Desk
will give you information on the nearest Regional
Immigration Bureau. The contact information for the Help Desk is shown at the top screen of the "e-Notification System".
According to their FAQ, re-submitting a new notification is the right way to fix any mistake in your old one. You only need to contact your local immigration bureau in case you want to cancel your notification altogether.