Sure, it appears that the 6 is upside down, but since the 3 and 9 are at right angles from the 12, we can easily see that the roman numerals are rotated so that their bottom faces the center of the clock. That means we are viewing a 3 and 9 that are sideways and a 6 that is upside down ... not a four. It's not wrong, and I've seen clock faces done like this before.
