And as soon as they get caught, the countries so offended against will call that (rightfully) a flagrant lie. The treaties were written specifically to prevent

And as soon as they get caught, the countries so offended against will call that (rightfully) a flagrant lie. The treaties were written specifically to prevent such a use of diplomatic privilege. That adjective "official" in the Convention is literally meaningless if a country is allowed to claim anything is "official", and trust me, treaty writers do not insert any words without a reason.