What specific behaviour is "calm"? You need to operationalise itI think I kind of meant reward for calm , or something!
Erm what is the dead dog test ?
I think clicking for calm is a bit pants, personally, because the click can build energy, which is the last thing that's needed if you're trying to lower arousal. Using a calm verbal marker is my preference in those situations - or not even a marker at all. If there's no precise behaviour, a marker is unnecessary. You can reinforce the less specific things with massage, stroking, gentle play etc. A marker isn't always a suitable tool.
The dead dog test (which comes from the dead man's test) is whether something is a behaviour or not. If a dead dog can do it, it's not a behaviour.
"Not attacking the cat" is something a dead dog can do. Therefore it is not a behaviour that can be either reinforced or punished.