Hey, thanks! I've just checked, and I think what you're describing is that the center of the triangle formed by the edges of a D4 is not in the center of the image - and that is absolutely true. That triangle is centered on the image bounds-wise, so that the lower edge and the apex are at an equal distance from the lower edge of the image and the upper edge of the image respectively. This doesn't mean that the digits will be off-center in the actual die face geometry.
I'm so sorry for taking so long to get back, but that's not quite what I meant. I've added a picture to show. All I did was export the face shape, filled it, then loaded it onto the same die. I guesstimate that the image of the font (or just a given image) is raised on the face by about 1.1%