I would just suggest to make some Windows-specific tweaks to the theme. This is mainly using `#000000` as the text color which native apps seem to use and then decreasing the size of the statusbar so it has the correct size out of the box (I'm not sure why on macOS `-3px` looks right while on Windows it's `-6px` - I suspect there's some bug in HiDPI scaling somewhere in GTK).
I created https://github.com/geany/geany-osx/pull/35 adding a patch that makes these modifications and I think this patch could be applied by the Windows bundler in #3129.