I’m finding the coolest people from all over the place gravitating to this forum 
Michael, you are a really, really helpful guy. Thank you for your blocks. You must be petitioning for sainthood.
Euroreact was the toolkit that let me sandbox with modular in a way that led me to finally take the plunge and get a eurorack system. I just plugged in my Isms system today for the first time.
In terms of getting things to communicate, I had the same idea as you: having the modules communicate with reaktor via cv and bypassing the osc translation issues. Unfortunately an expert sleepers module won’t fit in the isms case, but I do have a motu 828 mk3 that will let me send and receive DC coupled signals. That’s 8 ins and outs right there (leaving IO for monitoring and instrument ins), so I’m eager to get back to Chicago and hook it all up.
Euroreakt also helped me get to terms with things that sound confusing on paper but instantly make sense with a demonstration, such as an analog shift register. Thanks for your helpful demo ensembles, as they got me translating my musical ideas into patches pretty quickly. After watching how Kaitlyn Aurelia Smith and Cortini both use the Buchla Easel—namely with an ostinato coming from one side of the complex oscillator while they use the touch keyboard to improvise melodies with the other osc—I wired up this ensemble. Documentation in the ensemble-level info pane.
[EDIT: Upload repeatedly froze around 15%. Bummer. Screenshot posted instead. Sidenote: why are these ensembles with the new west coast blocks so huge? Like 50+ mb]