We'd need to implement some form of data store for values on Windows, which currently are not compiled in anywhere, and it would need a substitution syntax to be updated at runtime.

We're talking a big feature now, and you'd end up having just as much code on your side to make it work.

The only justification that'd make sense on our side is if we were going to bundle the tzdata file with the Windows installer, which doesn't affect you at all, apart from us then having an existing path listed that you'd want to override still. And even then, we'd probably preinstall the tzdata package which already overrides the path, and so there'd be no changes necessary to sysconfig and so we wouldn't touch it anyway.