It's quite obvious to anybody who knows how to right click that screamers are too powerful vs snubs. Making them immune to CD is not the answer, as then they become risk-free for the bombers that do nothing but run away from you while spamming them out. EMP guns are perfectly fine vs snubs and should be the main way to deshield them.
Make screamer radius, speed and acceleration lower than nukes, perhaps around the 80% mark. I fail to see how buffing their damage radius and hp will do anything but make them stronger vs snubs, rather than unviable, and they shouldn't be unviable anyway, merely reduced in potency.