Hi Kelly, again I'm quite new here and to Csound so beware with me :)

I may somehow be mistaken but my understanding of Gen02 is that there is no need to explicity  state the size of the table. From the manual:
size -- number of points in the table. The maximum tablesize is 16777216 (224) points. The value may be given as zero, in which case the number of values decides the table length.

The "behind the nut" timbres are likely just really high notes. There are a few ways you can deal with this if they annoy you. In the score there is a second instance of the Trigger instr whose p4 shows 1. This adds an octave to notes the second score entry triggers. Setting it to 0 will get rid of most of these but at the expense of muddying things up. You could also easily comment that score line out.

Another way to eliminate some high notes is to lower the max. iterations value for the mandel opcode. The higher the iteration, the further down the note table can be triggered therefore pkaying higher notes.

And I had noticed the XY regions that the XY number generators randomply reference return quite a few of the same notes, especially the highest note. I found one way to deal with that was to change the upper goalpost so to speak.

Here's a link with a small modification. There is the addition of an rspline which randomly alters the max. iteration from 12 to 21.
https://drive.google.com/file/d/1X1uMJaO19fOTrLDlq3QhhR_CUN2Wl5OH/view?usp=drivesdk

As always, any comments, tips or suggestions welcome, I'm here to learn. 
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