It was precisely for this reason that Cheng Ziang considered having Liseya invade a member of the Ghost Race to copy their memories and learn their language directly. And the reason he actively volunteered to pursue this Ghost Race girl was partly out of a sense of justice and partly to take the opportunity to target a lone member of the Ghost Race for invasion.
In the village, he hardly dared summon Liseya, since it was clear that the Ghost Race's high witch was no ordinary person. She might detect Liseya's presence, and then they, the outsiders, would certainly be watched.
The psychological pain of mental invasion is worse than physical pain. The latter is only temporary discomfort, but the former could result in the implantation of an unpleasant memory, becoming a lifelong nightmare.
Cheng Ziang could only pray that the bad memories Liseya left in the Ghost Race girl would be sealed away with today's events, so that the Ghost Race would not target him.