Before applying any changes, backup the current settings in an additional sheet. Allowing users the ability to then rollback any changes based on the contents of the backup sheet. Perhaps hive this off into original settings, pre group settings gopher AND pre last successfully applied? Just thinking here, LemonGrove. I made lots of changes, they didn't like them so they wanted them put back. I had to scrabble around for the original CSV to restore, the gui for this addon allows the potential to make this process really easy for a user.
Although maybe dont allow this if you're going anywhere near a Hapara domain as that 2,000,000 cell limit is going to get eaten pretty quickly.
Perhaps these need to be a predefined other sheets in the users drive to help with that?