Considering that the system detect the missile exhaust flash (I don't know on which frequency and will obviously never know), and can do it from far away in dcs, I don't understand.
I know what you mean. But still, it can be really slow to react. Not immediate, I can understand, but so late, it is not very useful anymore.
Here is a track demonstrating that (Auto-dispense ; steady flight, more than 500ft, shooting distance of about 2 km).
It is even worse if you adapt your tactic (understand flying low). They detect you later, shoot from closer, and the CMWS is totally useless.
CMWS Test.trk