I believe note off is germane to the midi spec. It can be used as a control separate from the note on. Duration is expressed with respect to the clock rate. Note off can have a velocity value associated with it as well.

 
Not sure what your point is, but if you read the test results I posted, you will see that it's the Note On arriving on the same channel of another port that cuts short the duration of a held note, not the Note Off.
 
In any case. I think the bug is extraordinarily well-documented at this point. No need to rehash it. We just need to get Cakewalk to address it.
 
Despite the failure to get confirmation from Tech Support, I would guess that Development are aware of this, and just haven't felt like it was the highest priority to fix. Though it's hard to undertand how such a basic functionality could be fouled up, obviously only a small minority of users use SONAR in a way that they would ever be affected by it.