AA has had variable seat counts by type in their fleet for a long time.
Just the narrowbody fleet alone in recent memory:
a319 - 8
a319 (LUS) - 12
a320 - 12
MD80 - 16
a321 - 16
a321 (Post Oasis/Kodiak) - 20
a321T - 10F + 20 J
757 (LUS) - 12 or 14
757 (LAA) - 22, 24 and then 16
Regarding seats, they all start with row 1 now. Starting with row 3 went away with the retirement of the MD80 and retrofit of the LAA 738s. Starting with row 2 ended with the retirement of the 763.
The major remaining inconsistency is the 777 fleet. On the 77W, the starboard side in First and Business is seat
J whereas on the 77E, it is
L.