Gulp refuses to process the LESS files.
Ahh, you must be using the gulp-refuse module 
You’re overthinking this and seems like you’re just reading chunks of posts instead of the full post or thread. See here: Sage with LESS (without SASS) - #4 by JulienMelissas
I successfully installed the original, LESS version of Semantic UI using Bower in about 5 minutes.
$ bower uninstall bootstrap-sass --save && bower install semantic --save
Then in assets/manifest.json change main.scss → main.less then go create that main.less file and copy over the wiredep block from the original main.scss (change the scss line to less).
I then just had to copy Semantic UI’s theme.config.example to theme.config within the src dir (really poor project dir structure). Result:
