I think the abruptly cut off notes are actually a feature, because they're using different samples (or at least, different cut-offs) for those short notes. That's one area where a lot of libraries fall short, because the cut off sound on a short note is very different from a long note (the dampers are choking off a lot of energy very quickly in the case of a short note). But, it's a real technical challenge to make a virtual instrument do this. When you first play a note, the virtual instrument has no idea if it's going to be long or short. It can't read your mind.
So, if it's going to be an instrument that can be played spontaneously in real time, it needs to be prepared to give you the long note cut-off, or the short note cut-off. It would be interesting for a developer to explain some of the technology they're using to do this. Must be some kind of timer. Pretty amazing that things are at a point where they're doing this. I would imagine that these are the kinds of things that can be tweaked endlessly (all the timings and volume levels that are engaged by relatively little MIDI controller information). So, maybe we'll see a revision that's a little better. But this is probably part of the reason that there are 4,200 samples per note in this instrument. Maybe to capture even more nuance will require 10,000 samples per note. It could be that we've reached the point where we need keyboard controllers that send more information about what a key is doing than just note on, velocity and note off.