I go through the code and found hermes is implemented by teammembers send the cooldown related information to you.

I found in the WOW, there is a event call: UNIT_SPELLCAST_SUCCEESSED, in the event, the unit and the spellname are all provided.

So is it possible to use this event to monitor the cooldown of your teammembers? Is there any bad performance with this solution, like impact the game performace, etc?

I write a small addon to do it and it look ok. But because of my poor programming, I only can write the simple addons for my specific char and also the specific spell i want to monitor.