If you want complete control over cymbal crash durations in Superior you'll have to program your cymbal envelopes to respond to after-touch. I never use Superior's pre-defined muted cymbals - I prefer to have complete control over mute durations.
To do this - select the cymbal you want in Superior, and look at it's Envelope. You'll see a toggle Note On / Aftertouch / Note off. Set this toggle to Aftertouch. Then set the envelope nodes like this:
Attack: 0.0ms
Decay/sustain: 0.0ms 100%
Hold: 0.0ms
Release: 22.0ms (you can play with this one to get a natural sound)
You'll have to program each cymbal individually. But once you program one, you can save the envelope Preset, and then load that preset for the other cymbals.
Then in the Sonar PRV, open up a new controller lane for ChanAft (after touch). Enter a high value event to evoke the cymbal mute. Wherever you put this control event is where the cymbal will mute.
For whatever reason, to get the best results, I always precede the high value controller with a low value controller - right before the high value. If I don't do this, sometimes the mute doesn't work.
There might be an easier way - but at the time I bought Superior, this was the only way to do it.
Hope this helps.