I just looked at the original and the copy through my laptop's shitty default equalizer. The copy has unnecessary bass. Around the 1k hz range. This is probably the largest contributor to what makes it sound hollow.

Also, just comparing them by ear. Over each note, the copy builds up and then builds down in volume in a <> shape. The original has a sharper attack and then fades gradually, which looks more like a > shape.

I think the copy also has an unnecessary reverb effect, but I'm not sure.

This is all malleable of course. None of this is the fault of the software. It's just a difficulty inherent to reverse engineering.