Don't you have the client "proof" the copy before you spend all that time working on the project? A simple proof sheet or proof email with the usual industry standard proof wording would easily transfer the liability for errors from you to them. As a commercial printer and
sign shop, I wouldn't print anything unless the client
signs off on it. I've seen situations where I knew something was spelled incorrectly but the client still signed off on it. But, its not my job to point out their mistakes, is it!