So which one is it? 68% or 80%?
Well I've since remebered lol Dammit! The discrepancy is due to 1 metric describing the power input vs the energy emitted after the phosphor losses, and the other metric is describing the power input vs the energy before the phosphor losses.
When I assume a CE of 1, I get ~3.3μmols/J. The stated claim is 3.03μmol/J, so I'm assuming the CE for the phosphor film they are using is not 1 but something close to 0.918. I'm going to wrestle a little more with this.