Hi Ian -
Thanks for reaching out and I'm thrilled to hear you've begun to use the platform. To answer your questions, if you were to add a specific tag to a selection of listings and also edit those listings prices and descriptions as part of a flash sale, you could then later find those specific listings by using the sidebar filters on the main listings page to search for listings that contain that unique tag.
As for the option to undo, or a way to revert listings back to a previous state, this is something we are currently exploring and plan to implement in the future.
Hopefully this provides a little clarity, but I'll be sure to keep you updated and please feel free to reach out at any time.
Thanks,
Justin