I'm in agreement with Ronin here...this build is all but useless. There's so much stuff missing that would be essential to a modular's operation that I can't even tell exactly where this build is going.
You need to back waaaaay up and study how synthesis works...not just modular, but in general. This build has audio sources...and then it's missing everything forward from that that should be in the audio signal path until you get to the Rainmaker and Audio I/O. The sole modulation source is the Black VC EG...but without filters, VCAs, and so on, that's pretty much useless unless you want to modulate the oscillators to make funny noises. In short, it'll be a rather expensive and unsatisfying not-really-an-instrument.
If you insist on going with modular, you need to understand how it works before doing the musical equivalent of tossing $3k into your fireplace. My suggestion would be to stop messing with MG for a while, and instead get a copy of VCV Rack (https://vcvrack.com/). It's free, it functions more or less identically to a Eurorack system, and it has a very extensive module set. Learn what does what, how, and why...and also why the UNsexy modules in a build are sometimes more important (when taken as a whole) than those really superduper ones with the blinkenlights and twistenknobs. And if you insist on spending money on a physical device, start with a patchable synth that has most of the building blocks you need built in so that you have a proper device to learn on.
This is a problem that actually crops up on here a lot, btw. Right now, you have a lot of people running around going bonkers over modular synths, thinking they're the new essential (sort of like the hysteria over the Roland TB-303 in the mid-90s)...but the fact is that unless you have some real sonic ideas and goals in mind that you know require something other than a bespoke instrument, and unless you also know the tech that makes those ideas and goals possible by having learned them either via a good text on the subject, various software tools like VCV Rack, or hardware that's already taken care of the module selection process, the end result will usually be a lot of money spent on an unworkable system.