The problem is that Omnisphere is Omnisphere...attempting to replicate what software can do is pretty pointless when you're talking about something on that level of complexity. I mean, I have Iris2 myself...but I would never try to make hardware behave like it, because it just won't.
Anyway, this build sure does look expensive. As in, some parts are pointlessly so. And there's loads missing; how do you expect to use the Doepfer A-155 without its companion controller module, for example? Where are the attenuverters? The submixers? Where are the modules that make these expensive ones actually usable? Oh, they're boring? Tough. They're also necessary.
First of all, take your ten most expensive modules in this build and find suitable replacements at a more sensible price. That alone will drop the cost of this down, potentially by over a grand. And make things SMALLER...84 hp is a lot tighter than you think!
Second, you seem to have some ideas of how modulars function...but the ideas still seem to have flaws (like thinking you'll be fine with only an external mixer...and if you think so, then how do you intend to mix any of your modulation signals?). Prior to blowing money on an expensive rig like this with limited functionality due to uninformed choices, I would strongly suggest getting a copy of VCV Rack and exploring how things work in that virtual Eurorack environment. Some things are different, true, but the BASICS remain the same and it's from that that one learns what parts must be in a synth build for proper functionality.
Definitely keep working...but not on this version.