I have the idea that extended's development was highly centralized, not that I mean to imply that this was the intention, but it seems to me that's how it went, so when it was abandoned, it was hard to take it further - I might be totally wrong in my analysis so please feel free to correct me.
The main problem was that setting up a build environment was way too complicated. Also, the build itself takes too long, and there aren't adequate tests to ensure the build completed properly.
I've improved the Windows build environment immensely just by leveraging msys2. But the new msys2 installer has a bug that requires an obscure workaround. Apparently the msys2 team already fixed the bug. But the lead dev is on vacation for two weeks, and guess who is the only person able to push bug fixes into the installer binaries... So apparently the free software ecosystem is full of problems like this. -Jonathan