Interestingly enough, "In A Mirror Darkly" might have been the first on-screen canon depiction of a Constitution class having aft torpedo tubes, but this notion to my knowledge dates back to Franz Joseph's schematic for the Constitution class. It depicts one or a pair (can't quite remember ATM, but I think it was two) mounted in the back of the lower bridge module, around the same area where the astronomical observation telescope is often shown.
Nope. As a matter of fact, all of the FJ materials place the torpedo launchers at the front end of the lower bridge module. The aft end with the telescope was always just the telescope.