I found the problem it's your settings.
Your setting Holy Radiance 6 Units Below 90%
In LFR there a very few chance that 6 unit stay together within 10 yard drop below 90% that the reason CR will not cast Holy Radiance. There are mostly only 1-2-3-4-5 guy below 90% and CR use a single heal spell (Holy Light, Flash of Light, Divine Light) to heal them up 1 by 1.
Try to set 3 unit below 90, it will cast more.
The default setting 3 Unit Below 90 is decent setting imo. If you have more/less mana, just keep the default settings and adjust the heal balancing slider.
New update anyway:
Better detect heal percent and increase healing done.
Cheer.
I'm testing a LFR 25M on Jin'rok, top healing and doing a solit 89k hps on ilevel 490, hope you guy with better gear will heal more.
Edit: Fight end, top healing, did 93k hps and 10% mana left. Default setting no heal balancing adjustment (I got bad gear :S)