skyeriding
901
As a matter of fact, you are correct - The pocket watches weren't symmetrical!
I did a quick search and found this article from timeandwatches, which has some scans of past Minerva watches. One of the photos show a rattrapante pocket watch, which does indeed, have the top subdial sitting slightly higher up than the lower one! (I verified it by measuring the photo digitally)
If I had to make a guess, this is because they have the liberty to do so from a design perspective, as the subdial at 12 would need some extra space to squeeze the "Minerva" logo in between. Technically, I do not see any restriction to move the minute counter pinion closer to the centre, with some slight minor shifting of the wheel locations. I think there's just barely enough space without interfering with the crown wheel that it is sitting on top of.
Photo from Time and Watches
Regards,
skyeriding