@ Morry. I made it back OK, though it was touch and go there for a minute, like being in the Logic land of Oz. "There's no place like home... there's no place like home..."
I listened to your track. I think you have bigger problems than your cello! For that piece, the first thing I'd suggest is finding a guitar sound that has more levels of samples so that the attack isn't so hard on every note.
As to the cello, let's talk about the second phrase where you play C, A, D (long note), C, and then the chord of A, C, F...
The first C is, say, mezzo forte (mF) but then the A that follows is very suddenly pianissimo (subito pp) and barely audible. Then the D, C, and chord seem to crescendo slightly from there but then the chord cuts off abruptly.
Is that subito pp A intentional? If it is, then I'd say that the guitar should follow the same dynamic. But if it's not intentional then the velocity on the A needs to come up. Or, if you created that subito pp with volume automation, you need to raise the level much more so that it doesn't sound like the cellist is unsure of the note he (or she) is playing.
The chord, A, C, F. It's very uncharacteristic of even three real celli to play a voicing like that. It has a muddy sound because of the register of the notes. Aside from the muddy sound of the chord, it's also uncharacteristic of an arrangement to suddenly have three solo celli playing where there was only one before. For purposes of realism (as well as arrangement) I suggest having the cello play only the melody note (F).
From a sound programming point of view, the release time (envelope 2) sounds like it's set too short. Lengthen it a little so that when you release the notes there's a slight amount of "ring". That will help the notes connect better.