Ive never used the light sensors, but I expect that the LED won’t emit enough ambient light to reliably detect. You also have to adapt for the wildly different lightings at events, so i would advise against using the light sensors. The line tracker has a range of just a few millimetres and actually detects IR rather than colour, so you wont have much success there either!
The best you could use is probably the newish vision sensor, however, these arn’t amazing in my experience.
So, your trying to detect cubes by making them break a light beam? if so you dont need to do this, just use a line sensor that almost touches where the cubes are going to be. When the cubes go over the line sensor it should be able to see a change in light and detect the cube