I really think PA just means that the panel configuration is what follow, kind of in the same way Devoucoux uses PX. jn4jenny mentioned in another thread that Bertrand from CWD told her PA = panel designation. Also, even PL saddles are stamped PA, which would suggest it’s not a pommel configuration. The only ones I’ve ever seen not stamped PA are older ones.
Perhaps the RT+ or the original custom thinning under the stirrup bar accommodated your need for clearance through the wither width-wise?