A small request: let's add a Fortress to the Castle. Without it, it's a bit difficult and unusual to buy troops, and it won't significantly affect the overall growth anyway. :)
And if it's not too difficult, could you move the observation towers one cell over? Because instead of just clicking where to send them, you constantly have to visit the tower.
And also, regarding the signs, after casting spells, you have to re-enter them, but there are already many of them; I'm not sure how much time you spend on this procedure.