Cast Delay or Global Cooldown on skills are no longer visible on the hotkey after the client change.
Cast delay should always be visible after casting a skill that has cast delay (on Limit RO, that would be EVERY SINGLE SKILL).
Seen here on a kro video dated 6th April 2017. At minute 2:46 of the video, the player uses Magnum Break causes all skill to have timers/cooldown (Skill Cast delay).
Magnum break has 2 second cast delay as stated here.