I've been thinking of something very similar to this and have been working on the implementations. I currently have front-ends written in Java (Swing and SWT), Pascal (Delphi VCL, Delphi FMX, Lazarus LCL), C++ (wxWidgets and Gtk). I also have a HTML/JS prototype. I have backends written in Java, C#, Go, Crystal, and Nim. For the protocol I'm using JSON via HTTP. The more I work with this approach the more advantages I see. I think you're on to something.
Based on the set of front-ends, it sounds like the goal of your project is a cross-language GUI toolkit wrapper. Is that correct? The goal of my project is a cross-platform and cross-language accessibility abstraction.
