You measure radiant flux with a spectrometer. A handful of members have them, of course some better than others. Djozz already tested this led (1mm^2 version) and compared it to white. He didn’t report radiometric power totals, but did share the spectrum and photometric data. If someone is so determined, the data can be back calculated.
Correction to what I said before in that the base emitter seems to be of ~20nm - 425 vs 445 - shorter wavelength. This could in itself explain the slightly higher Vf.
I’m not going to further chase you down on ‘proving you wrong’ since you adequately did that yourself in the respective areas any of us were contending you in.