It's not as easy as simply overtyping the invalid letter in your name field as a change would mean a ticket reissue likely triggering change fees or a reprice, or both, so normally the simplest solution is to attach a name correction to an remark field on the applicanle airline's PNR for the check-in agent & GA to see when the check your travel documents like passport.

It does get more complicated with multiple carriers but if it's just TG you should be okay to fly and then submit it manually after your journey if it doesn't post to AP automatically.

Good luck with your "X" rated ticket.