Thanks to Ing. Jaroslav Stepanek, I have measured the real light output on Brno University of Technology, Faculty of Electrical Engineering in integrating speher.

The expected value based on datasheet and measured current on full power was about 600lm, because of decreased efficiency of LED when heated and looses in optics and plexiglass cover, the real output was slightly over 200lm.

If you are interested in more details, check the github page!