I think I can solve this mystery.
1. Your watch is clearly intended to be a US model. You can see the "HON" import code on your movement.
According to Dr. Ranfft, that code was assigned to the importer "A. Hirsch", who worked with Universal, Tissot and several other brands over the years.
2. While the movement is clearly engraved "17 Jewels" and "Unadjusted", both of which were required to pass into the US without additional Customs duties on jewels and adjustments, there is an additional engraving underneath the micro-rotor. It says "6 Additional Jewels Swiss". Both this engraving and the import code look to be hand-done with a stencil. You can see it clearly in this picture from one of your links:
Of course, 17 + 6 = 23, so the dial is correct. Not sure whether this was a back-door attempt to avoid the duties on jewels in excess of 17 or for some other reason. In any case, there is your mystery.
GLWS,
gatorcpa
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