Constitution's transom's true appearance is very tough to pin down. Part of the problem is lack of surviving documentation, part is that
Constitution's appearance changed frequently, and part of the problem is that the transom was nearly destroyed in her battle with
Java.
Java was able to stern rake
Constitution during the battle - twice. Since the damage was severe, and initial repairs were made at sea, her rebuilt transom probably looked different than her pre-
Java fight transom. What changed and how much changed is not known with any certainty. Some have suggested that the number of windows changed during repairs either at sea or in repairs in port following this battle.
The best references for her War of 1812 fight with
Guerriere appearance are most likely the "Hull Model" and the Corne paintings - photos of each below. Her pre- and post-
Java battle appearance is probably a bit different for reasons stated above.
1. The "Hull Model" was built by
Constitution's crew and presented to Captain Isaac Hull as a gift. Her crew and captain obviously knew what the ship looked like and the model was built according to that knowledge. The model survives and is preserved at the Peabody Essex Museum in Massachusetts. The model depicts the ship with 6 transom windows. The model is significant enough to be used by the Navy as a source to determine Constitution's rigging configuration during a recent refit. Source:
2. The Corne paintings were made by artist Michel Felice Corne, commissioned to create a series of 4 paintings to commemorate her battle with
Guerriere shortly after she reached port. The artist was given considerable access to the ship and the work supervised by the ship's purser, Thomas Chew. Corne made detailed notes in preparation for making the paintings. The paintings may be the best references for the ship's coloring and appearance during that fight. Note that at that time, Corne recorded that she had a yellow ochre gun stripe, not white. But some of the decorations are recorded as being white. The transom's window framing is red as are the inner sides of the gun ports. Corne painted the ship with 5 transom windows. Like the "Hull Model", all 4 paintings are at the Peabody Essex Museum.
Corne, or a student of his, made another painting of
Constitution a short while later. That painting was featured on a US stamp and also appears below. Again, we see a yellow ochre gun stripe, not white, and red window framing.
Although the 15-star, 15-stripe US flag was the official US flag at the time, lasting until 1818, the Corne
Guerriere paintings show the ship with an unofficial 16-star, 15-stripe flag with stars in three rows, 5-6-5. The latter Corne painting shows an unofficial 17-star, 15-stripe flag, with stars in three rows, 5-7-5. (Tennessee became the 16th state in 1796, Ohio became the 17th state in 1803, Louisiana the 18th state in 1818.)
Note that neither the "Hull Model" nor the Corne paintings show
Constitution's name on her transom. Also note that the "Hull Model" shows green inner bulkheads, fife rails, and hatch and capstan trim, and the Corne paintings show the boat over the transom as also green.
Neither the "Hull Model" nor the Corne paintings show any gun ports cut through the transom. As you wrote, that modification came later, under Bainbridge.
The classic Revell 1/96 scale kit's transom is based on the "Hull Model".
Hope this helps.