Agreed. While not an expert, I feel like the bar for prong 3 has been lowered since I wrote the above - the original author has confessed to making it up, but Vance continued to promote the story after this and never officially retracted it.
Prong 4 still is tough - to have standing to sue you'd have to be someone who was harmed. So likely a member of the Haitian immigrant community in Springfield (of which I am not a member) would have to be the one suing, AND would have to be able to personally demonstrate damages.
Tough, but definitely possible within reason.
Considering what else is at stake, that person would need solid legal representation.
Assuming you aren't a member either, the most you could do is lend support to folks out there, maybe reach out and see if anyone who has suffered is interested in a lawsuit and connect them to the right legal firms and such. Which is still enough to go a long way.