Got hold of CIE Publication 15.2:2004 and on Table T3, page 35, D50 is listed as 96.42 100.00 82.51.
A fresh search in my stock Excel sheets also turned out the same XYZ for D50 for the weighted ordinate method.
Egg on my face... Hope this helps someone. But I don't know where the difference comes come... If you know, please, say something... I'm all ears :-).