Reflex 3.0.1 is a bugfix release.
It fixes the Python package structure, which was buggy and made it unusable. I also upgraded all NPM dependencies to latest versions, but that is only relevant for theme developers.
Reflex is now available on PyPI as pelican-theme-reflex. It can be installed as a normal package:
pip install pelican-theme-reflex
And then it can be used in pelicanconf.py like this:
from pelican.themes import reflex
THEME = reflex.path()
Now that Reflex is published I will try to get it included in pelican-themes.