Document corruption is happening too often. It may be difficult to avoid it happening in some obscure cases. We need a work-around, until we can provide a complete undo facility which is reliable. Consider the following:
Provide a means to fall back to a previously saved version of a document/variant, before it is shared. For example, retain the last 5 or 10 saved versions of a document or variant, up to the point it is shared. Once it is shared, only the most recent one is retained (I assume you will only share a document which has not bee corrupted).
Rather than redesigning the UI, a simple Undo Save button could be created (different to the normal Undo button - if we used that button we'd be changing its behaviour later with the full undo functionality, which would be confusing to users). The Undo Save button could result in a modal popup which would offer a selection of saved versions to the user.