No, that's backwards. It takes about 12 cups of water to fill the inner pot to the "9 cup" line. In other words, 1 cup as measured by the lines is actually 1 1/3 cups (or about 315ml). So, measuring with the lines gives you more than you want, not less (as you would with a rice measuring "cup").
And, the manual doesn't mention anything about the scale (although it does mention the "MAX" line at the top of the pot).
Here's another guess - my rice cooker has line for cups that are for filling with water after you add rice. So, in your case, you put in 9 cups of rice, then add water until it is at the 9 cup line, then that's the right amount of water. The water fills the space between the rice and then fills up to the line.
And, the manual doesn't mention anything about the scale (although it does mention the "MAX" line at the top of the pot).