Sounds like a recipe for disaster. Did this come with a special drain? It may work, but in the long term, I don't think you'll be satisfied.
Suggest you try asking this at www.johnbridge.com. This is not one I've dealt with.
It appears that you have studs that you attached the cbu to. That needs a vapor barrier behind it, then the barrier should run down into the shower pan. By code, the waterproof pan must run up 3" above the curb. If your pan is only 2", and it is full of cement, it doesn't meet code.