So after 2 years, 2 burned out LEDs got replaced & the blue LED voltage got reduced from 7V to 6.7V.  A few more diodes got replaced with shottkys to try to even out the brightness, but some of them barely light up & some of them don't turn off all the way.  A lot of diodes were shottkys in the original circuit.

The problem of uneven brightness in the blue LEDs is bigger than originally envisioned.  The LEDs aren't matched & the strings are different loads.  Shottky diodes didn't make any significant difference so the diodes aren't the problem.  Every single string would need some kind of adjustible resistor, a very expensive proposition.  There's also the problem of flickering.

It would have looked bad in the 70's with only discrete analog circuits like this, so thoughts of redoing it all with a microcontroller have abounded.  In fact, the lion kingdom vaguely remembers electronics looking this bad in the 70's but it only being bearable because it was all we had.   It's not about the work as much as losing the retro appeal.  At minimum, doing it once in pure analog showed it wasn't practical in pure analog.  There could be a simpler art piece based on pure analog & simpler strings.  The microcontroller would expand the effects.