The difference between the two back lights is that one is made up of 21 LEDs (7 rows of 3) and the other is made up of 30 LEDs (10 rows of 3).

To see a difference in the brightness of the backlight between the standard and high-bright displays you will have to apply more overall current to the high bright.

If you are driving the LEDs with 190mA in both instances you will not see a difference in the brightness between the two because you are simply distributing the same overall current over more LEDs  (i.e. at 190mA you are supplying about 27mA to each of the standard LEDs, but only about 19mA to each of the high-bright LEDs). 

What you want is to apply the same current to each of the LEDs, not the same overall current. For example, increasing the high-bright supply to about 270mA will give you 27mA across each of the 30 LEDs (same as the 190mA applied to the standard version) and therefore a brighter back light.