Since neither the older C nor the newer Java versions of Electric are being developed, my idea was to fork the C code. That is the one that was actually used commercially for IC design and the one that I had some experience in. I have no idea if there are improvements or bug fixes in the Java version or if it is a simple rewrite. Of the many rewrites I have seen, the only one I ever saw any value in was the change in Spice from Fortran to C as the original code's memory management was just too horrible due to Fortran's limitations.
About KiCAD, it works great for the PCB sizes we use. But imagine trying to design a printed circuit of 15 meters by 20 meters. What changes would be needed in KiCAD to make this practical? This is what designing integrated circuits is like - the ratio of feature size to project size is four orders of magnitude or more.
-- Jecel