Yes, the name is a corruption of a Chinese name for Japan. So what's your point? Japanese is not the same language as Chinese; it isn't even related linguistically other than borrowing part of its writing system.
It's basically like making up a name for the UK based on a corruption of what the Romans called it 2000 years ago, and then trying to claim this is similar to what Britons call it today.
It's basically like making up a name for the UK based on a corruption of what the Romans called it 2000 years ago, and then trying to claim this is similar to what Britons call it today.