The CP bonus is not given to the one who fights more kql. The CP bonus is given to the underpopulated Faction in an effort to balance out the Faction populations and make the game as fair as possible when there are no restrictions which Faction to choose when a new user registers.
From what I can understand from the war report, the Dark Faction is fighting fiercely as well, which is why they got the max CP bonus. It is clear that the Light Faction is fighting more efficiently, but it seems that the Dark Faction has more players who can generate higher CP than the Light Faction has.
If the Light Faction can continue like that, and assuming no other changes in the populations or CP generation per Faction occur, then it will have the upper hand as its players evolve and can generate more CP per battle.
Another thing you may need to consider is not the amount of battles fought by someone or by the Faction as a whole, but the "quality" of the battles. I can do 10 battles in Normal which will generate 100 CP and someone else can do 1 Suicide which will generate 150.
As you can understand, numbers may show one thing, but with a deeper and more careful analysis you can reach to other conclusions.