How does that even happen?

Climb in VS with too slow and/or decreasing airspeed, then level at too high of an altitude where the airplane is pushing air and continues to bleed airspeed even after level-off?

I'm not and never have been a SKW pilot so I cannot comment on your procedures, but as an outsider it would seem like a combination of 1. pilots not paying damn attention and 2. too slow climb and/or cruise CI speeds - is that accurate?

For everything the CRJ is and isn't, it does just fine at altitude if you keep speed on the wing...