degen "I can't find the EW2740L (measured at 11 cd/m² at 0% brightness)"
Do you also take down the RGB channels from the default 255,255,255, and reduce the contrast level? That will allow you to get a much darker screen at 0 brightness, probably too dark even on units known for being too bright.
I just read this: "and I kept the OSD contrast at 10."
So you've done that already, but what about taking down the RGB channels? That will make a big difference.