Words that are considered curses in modern times are only because society defined them as such. When the Torah talks about someone cursing someone, it doesn’t mean saying a bad word. It means wishing evil on them, and actually saying the wish – “May Hashem cause this and this to happen to you.” That is a curse that the Torah was referring to.
Using bad words today probably falls under a chillul Hashem, because people will look down on Jews for it.