Well, first off...it's really...ah...BLACK. But that's not good. Invariably, if you're creating a Eurorack along a certain look, then all you'll wind up with is a decorative prop. You've done a little bit better than that, but at the same time there's weird flaws here. A 4 x 84 rig with only four VCAs is definitely a flaw...especially if you're trying to do lots of percussive work, because you need LOTS of VCAs for that sort of thing unless you're using percussion-specific modules (Tiptop et al).
The MIDI implementation is frankly lousy. You're running two of these mBranes to get 8 channels; why not dump BOTH and go with something from Expert Sleepers that fits in a similar space but which can be expanded AND provide a return channel for timing, digital audio return, etc?
There's an Elements...and a Rings? OK with the Department of Redundancy Department, perhaps, but a waste of space otherwise. Lose one or the other.
I could go on, but really, I think you've poured waaaaay too much effort into creating the synth version of the 2001 Monolith here and not enough in basic, practical modular design. All of these Mutable and clone modules might look awesome, but by ignoring very basic, boring-as-hell utilities and basic practicalities in favor of optics, well, it's a nice prop, and you'll continue to be frustrated. For example, your modulation source issue...you actually DO have ample modulation here, but because you've omitted utility stuff such as attenuverters or CV/mod VCAs, it seems like there's not enough when the real fact is you've just not got ways to implement what you have already. And having some of these huge, sexy modules means you're ignoring much better options in your "junk" rack; for example, I would think that using the Doepfer Wasp and Yusynth Synthacon VCFs would provide way more timbral character than the two resonant filters on the Shelves. And so on.
Musical instruments might seem like a fashion statement, but consider: is it important that Ornette Coleman plays a plastic sax, or is it more important that it's Ornette playing said plastic sax? Don't worry about looks...but be a lot more concerned about the music.