Very ambitious and looks like quite an accomplishment! I've been working recently on several DSP projects, including for web and embedded applications, and I definitely appreciate writing performant code without having to write C++ by hand.
I couldn't tell from your post and linked material how the runtime works — I see that the high-level graph is handed over to the runtime, but is it interpreted? Compiled? Does it require platform-specific binaries?
For my current projects I settled on Faust [1], which has the advantage of compiling to C++ source files (which can then be used with any platform/framework that supports C++), but that has the disadvantage that swapping components in and out (as you describe in the linked article) is not so easy.