Okay, there is a slight issue. If you take the entire datewheel as 360 degrees, and divide that in to 31 sections, you will find that each day occupies 11.612903 degrees of space. In the illustration below, I've set the first digit in the 3:00 date window, then rotated it by 11.613 degrees several times. As you can see, by the time it gets to the 4:30 date window (45 degrees away), the digit has picked up an extra 1.45 degrees, causing it to sit slightly low in the date window.
This goes a long way in explaining why nearly all of these tricompax watches that don't have custom datewheels, have the font sitting too low in the date window.