The CVR and FDR are for accident investigation and ONLY for accident investigation.
I would hope that pilot unions across the World would threaten strike action if they are used for anything else. (Yes I know they have been)
Would anyone who works in an office permit their every move and comment to be recorded and possibly used against them by their company or the courts? Can you imagine the screams of outrage?
We, magnanimously, permitted CVR and FDR to assist accident investigation and to avoid repeating errors; not for greedy litigation!