Chrono Dampener was nerfed recently, but I don't think it was enough. I couldn't even tell you what was changed about it because it's still broken.
The issue with Chrono is not directly the frequency or duration of the stun, but the fact that the stun will bring units to an immediate standstill. After the stun expires, the unit movement speed will be 0, and it has to reaccelerate to its max speed, which can take a second or two. Sadly at this point the next stun will have hit, bringing the movement speed back down to 0.
So, not only does Chrono stun units, it also significantly slows them down. This makes chrono extremely powerful (basically unkillable) when the ACU is retreating. I believe the best two fixes would be, in order of preference:
- Allow units to keep their momentum after being stunned
- Reduce the frequency, but increase the duration of stuns to allow units to get back to their maximum speed, and maintain it for a longer period of time