I have been wondering for a long time if it's just spoken words that the Qestir don't trust or if it's even written or if someone were to use some form of Hand talk or ASL would they treat you the same way as if you had spoken?

I know in some other fantasy and sci-fi that some races that are like the Qestir that it's just spoken word as they believe that words when spoken have power or it's easier to lie with one's tongue.