I wasn't able to find a good PT2399 chip that didn't have white noise and sync'd with the tap tempo lights. Must have tried like 25 of them...
All PT2399s have white noise, especially past 300 or 400ms! That's why I put a tone switch, to darken the sound (3 position) and achieve longer delays without too much noise. Or you could have a look at how the De Profundis or the Hamlet delay do it.
I raised the value of C12 (from 100n to 150n) cause I think it helps with the noise too.
I did notice the Feedback control, at max, would feedback like crazy, but also increase the volume to unbearable decibels! Worst I've ever heard.
My build will oscillate for sure, but not that loudly. You can try a pair of back to back 1N4148 from pin 1 to pin 2 of the feedback pot, it will limit the volume of oscillation. If it's too much limiting, then try a pair of red leds.
Also R4 is a larger value in my build, which helps.
Where do your PT2399 come from ? None of the ones I got from Tayda worked with the taptation chip, they couldn't sync. The good ones I got from Musikding sync better, some of them perfectly, some of them just well enough.
Oh, also, WOW that looks like an INSANE build!! We need a proper build report with gut shots!!