In the UK there's a common law thing called "passing off" that's used to protect unregistered IP from impersonation. It's already used to protect unauthorised abuse of voice actors IP.
I'm pretty sure "passing off" requires the seller to be fraudulently claiming the goods are the goods of someone else, that if you up-front say "the voices used are generated by computer algorithm and do not represent any real person" that a claim of passing off would be rendered moot.
Trademark/Copyright can't be disclaimed in this way but Passing Off requires active deception AIUI?
You're right that being clear to avoid confusion is a good preventative measure, but you're wrong that intent to defraud is required. It's enough that the public is (or is likely to be) confused.
See Reckitt v Borden (1990) judgement referring to the three-part test for claims of passing off (my emphasis):
"Second, he must demonstrate a misrepresentation by the defendant to the public (whether or not intentional) leading or likely to lead the public to believe that goods or services offered by him are the goods or services of the plaintiff"
