It's auto-brightness features on the other hand should work fine, and is something not really available from CF.lumen. Maybe one day one app will also be able to control the other.
I would love to include a logcat, but I simply don't have the time today or tomorrow. If needed, I'll post one this weekend.
When the app runs for the first time: grant su access, then I see the "please install cf.lumen driver". I click install, device reboots after a few secs, after reboot I wait for some time before opening the app again. When I open it, it asks me the same thing: install the driver. Wasn't the driver installed, or doesn't it detect the driver?
PHONE: Nexus 4, ROM: Paranoid Android 4.2 BETA 4 (that's Android 4.4.2 if you don't know), KERNEL: franco.Kernel #204.
On my first try I had Nexus Display Control (also by Franco) installed. My guess was the apps aren't compatible. After uninstalling both apps, reboot, installed cf.lumen again, install driver, reboot: same problem. So for now no cf.lumen for me. Just eye strain.
I hope this helps you find the bug or incompatibility I have!