So AB and JK not AC and HK. Very confusing naming as that deviates from the old B and J are middle seats caveat

As far as I can remember, Swiss allways used these letters for their A330 & A340.
Just the MD11 was different, but the 3-4-2 seating (ABC-DEFG-HJ) is a thing of the past, too.
You mean "really old" like on Swissair's B747?