As a lawfag this is what we called metadata. So many cases we lost and lawyers sued for malpractice because any documents formally sent to the opposition attorneys ELECTRONICALLY (when e-Law first started) allowed the other side to view EVERY DRAFT and ALL EDITS (including client input) which was performed before the document was finalized and sent. So the other side could see a lot of info which would have otherwise been subject to an attorney-client and/or attorney work product Privileges. It was a clusterfeck until it was straightened out.
So, in this case of redactions, if someone accessed these e-filed sent texts or emails which were redacted, you would be able to “peel off” the redactied black editing. But you would have to have actual e-copies of the original documents sent, e.g., like downloading a public court filing from a court or public website. Generally, that’s the idea. The redaction is only an electronic keystroke layering which could be undone.
I hope this makes sense.