I think the "JC t*rt*r*s demonic cultivators to d**th" thing is hearsay since in-story, rumors are presented often as unreliable and you think it'd be mentioned beyond LSZ and LJY and an innkeeper gossiping, in a time when LJY was also operating under the assumption WWX was evil.

Not really taking into account the innkeeper's testimony, where it's obviously a "a friend of a friend of a friend heard that" type story (and also such stories are framed in the case of JC's brother already to be untrue and exaggerated and overly villify someone)

Also, you'd think someone would've brought this up after the second siege esp since LSZ and LJY were the ones mentioned the rumors first. You'd think someone would say if it were a widely accepted truth "hey sect leader jiang we are not going back to your m*rd*r dungeon house"

So if he didn't do all that (which I maintain that he didn't, because Jin Ling is a child who's surprisingly normal given the hypothetical m*rd*r dungeon upbringing), I would like to present something I think he /did/ do that led to the rise of these rumors in the first place.

I think that, given Jiang Cheng's own history with demonic cultivators, as well as his role in training the disciples of Yunmeng Jiang, he'd not only managed to salvage the Yunmeng sword forms, but also developed methods of combat suited to battling against demonic cultivators.

When JL says he'll br**k WWX's legs for using talismans on him, JC responds with, "Haven't I told you before? [...] Feed him to the dogs." pointing to either passing on his desire for vengeance, or also, possibly, aforementioned combat methods against demonic cultivators.

I'd be rightfully scared of the dude who brought a sect back from the brink, rebuilt a stronghold, preserved an incomplete series of sword and forms, and on top of that, developed a fighting style to go toe to toe with a necromancer and their legion of the undead