Your halo waypoint profile isnt loading completely for me, but I will say that the campaign commendations most likely wouldnt be completed on one play through. if you have 50% that seems like it would be about right to me
If on top of that its showing numbers like grunts killed: 4/100
that is because the commendations are completed in tiers. you while you might have actually killed 204 grunts, it will still say you are at 4/100, because you are on the 4th kill of 100 on that tier