Out there isn’t any, as far as I know. You have to hire a dev and there isn’t any qurantees such plugin will work.
That will increase costs relatively much and then it is totally acceptable ask if your client is willing to pay for changing one word that no one sees or uses.
If an user has to look at url to understand where he/she/it is then UI is really badly designed. That is not situation on Discouse.
I’m not totally sure, but is there a chance you are trying to use wrong tool now?