Teach them sign language, while young when it's really easy to learn (harder for us adults, though apparently not hard either) - it could open up a lot of doors, and if I'm not mistaken it's somewhat internationalized? If enough of the new generation groks that, imagine what it does for communication.

Teaching them a new alphabet nobody uses won't help anything, other than theri own shorthand - but that can be improved even better by teachin ghtem real shorthand.

Also consider having them learn a second language - Mandarin probably. Throw in a romance language and they'll have no trouble learning new languages in a snap throughout life.... they'll naturally see patterns and grab concepts adults who grow up with a single language/alphabet don't.