You could possibly calculate the absorb by regression using other heals (which gives you the healing power) and character level. There would be a margin of error correlating with the number of heals and not all absorb shields might be fully depleted, although at least for nightmare operations this is generally unlikely.
At least for juggernaut tanks this would work great since the barriers have a static value and at least the Sonic Barrier is almost always used entierly.
It could still be used as a tool for meter padding by placing bubbles on every raid member whether there's group damage or not.
My recommendation (if he doesnt see this i will tell him at our next op) would be to just have a metric for amount absorbed by each raid memeber. Whether that is blade barrier, force armor, diversion, energy redoubt, etc. It could conceivably go under a number of different sections, perhaps even have its own and and a break down of the source by ability (since that would be way easier than caster in the case of force armor). Then there could at least be something.