But just to make your expertise a bit clearer:
Here's a picture of my 2012 Honda City driven 29K miles in 6 years but according to your calculations it should be somewhere around 60K-70K. And probably the only reason it's even at 29K is because I drove it to Lahore a couple of times; but again to be exactly precise 3 times, so thats another 3K I drove otherwise it would've been at 26K.
On the other hand my 2015 Toyota Corolla is at 98K+ miles in 3 years and thats because it's one of the those cars which is daily used on the long-route by the driver for my dads transportation. And supporting your logic the car should've just technically been at 30K - why the excess 60K?.
Back to my CL9 2003 | imported in 2003 - Which has 84K+ genuine miles because that car has been driven approximately 300-500KM in a month at max - Wasn't even driven for 3 years I was abroad for my studies.
To my other current car being the 2018 Honda Civic which I received last-month on the 27th still has only approximately 450KM because again just driven for short-distances. And I'm sure it'll probably be driven around 30K maximum in the next 5-6 years to come before I decide to change it.
Sir, your estimation is correct on the only possibility that the previous owner of the CL9 probably only owned that particular car and drove it around everywhere which I highly doubt to be very honest. By having ownership of more than just one car it's a possibility that Accord's can have actual lower mileage. And those particular Accords when sold in the market will definitely have one hefty price-tag along with it.
But I suggest that you stick to the topic - which is to help out the fellow friend here provide insight on this beautiful car he's interested in.