the only canon one is kanda and yes he does cuss. he's not foul but he Makes A Point

legolas... does not really swear in canon but maybe some of his euphemisms are disguised swear words, who knows

i think he's pretty loose in silvan/elvish though

but he learned Proper Common/Trade/English so he Doesn't

...usually.

neah.......... would. if he wants to.

sauron: first age sauron did a lot. working for morgoth kind of equals frustration and swearing

uhhh eregion-era mmmaybe not as much. he mellows out and goes kind of Nice. i mean he's still awful but the swearing is confined to non-curse words

after that he's just prefers the non-cussing swearing. the 'your mothe ris a hamster' kind of thing

who else do i rp

uuhh merlin escape devildom did not cuss much at all from what i recall in the webtoon

1903!14th / whitey is too polite to cuss. he's a bit murder happy but he's nice about it.