So looks like he didn't lie. Just used conventional jargons to market his product. When the parts are replaced from Toyota Dealership, they are original and that's what he mentioned.
When your cousin sold the vehicle, it was a company maintained vehicle and now it's a junk when he is selling it. Its not your responsibility anymore and the interested people should get the car checked on their own from the dealerships or their mechanics like the seller did. If he really have tempered the meter, that's wrong. Again, it's on the buyer to verify everything before investing. If anyone doesn't, the seller is not a fraudia, the buyer is a fool.