It says 23 jewels, are they not meant to have 25?
Yes, it should have 25 jewels inside. The odds are the rotor is not original to the movement, but from another compatible movement like a 2842 which has 23 jewels, and would explain why it's engraved with 23 jewels. I am only looking at the engraving on the movement itself, the balance and shock absorber.