Cooldown reduction

[Thieuke]

So I know CDR is capped at 40%.
And I can get there with 20 DEX (=10%) + 8% total from talents + 12% total from imbues and 10% from staff of mending.
But does the Primordial essence passive of Erwydra (=10% CDR at 60% filled gauge) stack above the 40% cap?
Also does the Master sorcerer talent (10% CDR for ults) stack with the cap and the above passive?

I currently don't have the resources for the staff and the imbues to test it out myself.