This one seems important, but practically a refund scenario is rare, and there's no guarantee every eCommerce hook would be able to do a reversal (depending on exactly what it is doing).
So currently we are just documenting clearly in the new version of the eCommerce tutorial what to do to do a reversal.
If implemented it should work well with the sales log. Deleting a sale would provide a checkbox to also reverse the purchase, or a message if it is not possible for a particular product.
So currently we are just documenting clearly in the new version of the eCommerce tutorial what to do to do a reversal.
It would be a nice feature though.