Are you sure about that? I always thought that Zhao Min @
http://www.zhaomin.org was translating from the first edition (just the Indonesian translation) and things are somewhat different in her translation:
Xie Xun still learned Kongdongs Fist of Seven Damages, however he also knew 3 (well 2 1/2 really) stances of the HL18P that he managed to pick up in his search for a skill that could defeat his teacher Cheng Kun. Supposedly he learned those 3 stances from a recluse he met, but one of the 3 stances was either incomplete or slightly wrong so it's power was greatly reduced, I think that this story is rather believable.
In fact I think some of the details in the first edition make more sense, for example in the first edition Z3F only cannot heal Wuji's poisoning by the Xuan Ming palm because Wuji's original internal strength technique was thought to him by Xie Xun and it reacted rather badly to the Xuan Ming palm (partly because Wuji had not fully mastered it yet). This seems more believable to me than Z3F and the remaining 5 heroes of Wudang beeing unable to remove the Xuan Ming palms poison simply because it is too powerfull for them...