The only reason Japanese is on that list must be because of the writing system. I can't imagine it would be on the list if it were only about learning grammar a

The only reason Japanese is on that list must be because of the writing system. I can't imagine it would be on the list if it were only about learning grammar and pronunciation. And when that's said - the writing system isn't actually hard, it's just that it takes time to learn it. There's nothing there that's difficult to wrap your head around.