Oooh, that's a good one. And a hard one! The first thing that springs to mind is actually an anime movie called Your Name, which is bodyswap shenanigans and has a written communication element as well. It's SUCH a good and beautiful movie, if you haven't seen it already. If you HAVE seen it already, there's a far less quality Wangxian fic out there that spoiled me for the movie (but did not ruin it, because nothing could), but I can't find it right now.