In the last MUD I played, if you were fluent in a language, you could enter a tiny bit of code to write your letters in that language. Similarly to Sindome's current speech coding, if you know the language you understand it, if you don't, it looks like garbled nonsense, and if you're a little savvy you get bits of it.
Without having a good sense of how the code works I can't make a suggestion for how to do this, but it would be very cool to pass notes in languages and have another need for people who speak different languages to get paid to translate.
Probably the grid wouldn't work since the IC keyboard would be in English in the Dome, so we get around having to try that. Just pen and pencil style writing.