Here’s the introduction of a new Google Sheet Add-on called Edit Form Submission. It originated as a simple Google Script but then became extended into an Add On.
Edit Form Submission uses the Timestamp to match up the form entry with the result on the spreadsheet, thus providing the re-edit link. In order to use it, the user must be the owner of the spreadsheet and there must be a form attached to the sheet that is currently allowing responses.
The add-on can be used as a simple form notifier, but is designed around the ability to provide form users with a link to be able to re-edit their form response. Normally this link is lost unless they click it immediately, but this add-on provides a customizable message to each form user that can include their link response.
Finally, there is an option to be able to record the link to re-edit the form on the spreadsheet itself. This allows the sheet owner to have a master list of all of the re-edit links so that if someone loses their email, the owner can send the link manually.