In a technical sense, any language filter is doomed to fail. You can take the 4-letter word of your choice, distort it a bit, bind it to a key, and go about swearing merrily without being caught.
In a practical way though, a filter may have some use. It can serve to signal that respectful behaviour towards fellow racers is expected. It's a barrier, however slight, for gratuitous use of bad language. But there are two things to note.
First is that the filter shouldn't be the only measure, else it will be an empty shell. It should also be mentioned in the rules, and there should be a place where you can complain about someone's conduct (same as when you report a wrecker).
Second is that the filter must not be too blunt, else it will backfire. If someone is banned at his first 'wtf', he may be tempted to come back for revenge (since dodging the filter is easy).
(Personally, I see no use in language filters. I prefer to look at the intention, not at the form. My kids, 4 and 6 years old, hear me swear often. I don't mind; I don't think it's "language not suitable for children". And I also don't mind if they swear. But I'd hate it if they saw me being mean to someone else, just as I won't allow them to intentionally hurt someone.)