doesn't update until the turn AFTER the change.
Oh, THAT...! Yeah, seems that's the ...
Concerning the scying pool:
Hmm, iirc when I built a scrying pool in an earlier release version the additional essence slot appereared immediately.
But obviously the update on next turn rule doesn't always apply anyway. In my current game I upgraded my town to Slums and the +3 growth showed on the stats immediately while when building an improvement that raised growth it in deed updated the NEXT turn.