You can’t know but I really don’t think this is a problem like you think it is. I can’t think of what the benefit of doing this is. That said, yes an additional copy from an independent source would help. I like to listen to the audiobook while reading the text so it hits two senses. You could try that. Also, you can download from sources where people can and do give feedback.
Yes just like paying for vpn and/or seedbox to safely torrent.