I think it might be a good idea if some Fiverr staff with some training in copyright (if copyright lawyers would be too expensive) could check the buyer requests for copyright issues (requests asking for stuff that would likely be against copyright law) or checking conversations/being available to join conversations if there are any questions of copyright there (eg. a user asks for something which could be against copyright law), ie. basically to say whether what is being asked would likely be against copyright law and state would could be done/what would be lawful, so both buyer and seller have the advice of one of the Fiverr copyright specialists.
I don’t think Fiverr has the inclination or manpower to police gigs and conversations on this level. It’s not Fiverr’s responsibility to patrol client-seller relations. This is the responsibility of a good seller, not Fiverr’s staff.
Well there’s already a “report” button on the conversation, where staff will look at it. It could have something similar where one of the staff with some training on copyright law could look at the conversation when asked (by a similar flag) and give a short comment. Maybe with a short template introduction. eg. “user x is correct. Doing x would be against copyright law, however y would be acceptable.”.
The template intro could say something like “Hello I am x, one of the Fiverr copyright specialists…” (with maybe something like “we check into messages with potential copyright issues/mentions”…