2.4" LCD TFT backlight current limit resistor
Yes, you are correct, however it might give you more even backlighting if you used 4 resistors that equal ~19 ohms in parallel. Eg. 50, 100, 100, 100 for K1..K4.
I would also check to see if the display is adequately bright at 50 or even 33mA. At lower currents, any imbalance in the white LEDs may appear worse because the resistive term in the Vf of each LED contributes less drop