That… is a pretty odd way to hold a tea cup in the third page.
Also, while this whole semaphor based telegraph is pretty cool in itself it feels a bit out of place in that world with dragons and people fighting with swords in plate armour. Pretending your overly advanced technology is merely magic is an interesting twist on it though.
So they're using a terminal as a front end for a remote semaphore system. That's actually really cool. You see semaphore networks a lot in time travel stories in the west but I haven't seen them used a lot in manga.