Wow! that's some bunch of spaghetti hanging down. There are numbering and lettering ID sleeves avail, but , of course, this relies on the wireman logging them....never mind, the punter pays and they're all stinking rich.
Seriously, I don't think there is any colour-coding system that would do the job. Even in the Automotive world,harnesses have multiple duplicate codes,but at least they can be used to narrow-down the search.
AIUI, Kapton has been found to degrade and crumble.that strikes me as potentially more risky than PVC or silicone.
The other issue that strikes me, is how thin the wiring is! Yes, I know weight is an issue, but ,unless the currents are very small, heating will be an issue.
Perhaps a professional can enlighten us?
I do know an industrial-machinery manufacturer who deliberately left his harnesses unmarked........in case of damage or a disconnect, the customer was forced to call on him for repairs as ha retained the diagrams that showed what connected to where!
not very ethical, but a good earner.