no worries! they're long lived enough to take their time with their business, so they can text each other cute pictures of birds that might or not be slightly blurry and laugh it off like old men do :')

planning through letters sounds absolutely endearing to me, though! the real penpal communication. either one also works just fine, but i might lean a bit more towards liyue just because it's not a ship in space with fake oceans lmao