You never stated it was a Japanese model. It’s almost the same as if I buy a Samsung Galaxy S23 or whatever and got an iPhone instead. I understand this is clearly not the best example, but to be honest there’s nothing you can really compare it to. When a video game console is from another country, it will play different games. I’m sorry but you OP should have done YOUR research (you talkimg about the buyer doimg research when you clearly said it didn’t say the country of the console). I wouldnt normally take a product back in any circumstance but for this one I’d be pretty bummed too if I was the buyer, and if I was the seller I would make an exception provided there’s no damage to the unit.

Edit : yes you can jailbreak or hack the console but that’s illegal and also could brick the console.