Riot Ban System is run only by bots and that is disgusting
so i had a game where i got flamed and responded back with same words as enemy (which is now i understand a punishable thing) and i got autobaned for 14 days because the word in question was "kys" which is a big no no i suppose, but the guy who flamed me got out with it just because he put $ or something instead of S. So i went to send a ticket to riot and argued with rioter for a while and when he was out of arguments they started sending premade bot responses again saying how problem is solved when obviously it is not when i can see the guy still playing games.
So in conclusion you can only be banned if you say a buzzword on a riots "weary bad word list" and bot detects it, otherwise there is little to no chance of you getting banned even if rioters know you said said words,trolled,fed, or harassed in any other way.