Ah thanks. I've fixed that section now
Right, Warcraft Logs looks at this +10CP and marks the excess as waste, but checkmywow does try to get the number right. Assuming that proccing at 0CP is ideal, if it procs and you're at 2CP, it'll record 2 wasted combo points.
I'm not too familiar with the actual gameplay though. Is trying to drop to 0CP before proccing again the correct way to play? If not, I'll adjust the numbers here accordingly.
The 1 combo point refund is marked as a separate thing. I think it's what shows up in the graph as "Combo Point", and shouldn't really have an effect on the waste calculation.