Thanks for digging into this.
If newer DMD versions (for a few years already?) link with lld-link instead of optlink, we should support that fully, and ditch support for ancient DMD versions that link with optlink. I'll rewrite the Windows build notes accordingly.
Happily, the main way to build Lix on Windows is with LDC (instead of DMD), and LDC building/linking will not be affected. DMD is mainly useful for working with the Lix source code; DMD offers the speediest compilation.
-- Simon