Earlier quoted context omitted.
The audio fingerprinting is used by services like shazam to identify music, not a per user re-encode of every single song in order to find out leaks. The watermarked music files I have come across only go as far as identifying the distribution service, not an individual. From what I remember the metadata of account information is added as an editable extended tags. I actually don't know if audiobooks are even tagged…
the real question is: why not lend some brain power to an open source project? or write some kick-ass documentation... and always get involved in your local community project /s
or not to be