The question is do you guys think this project is too complicated for a beginner in arduino.
No, not at all.
You were already able to get two sensors to cross and turn on the LED when both were blocked, so now you need to add a second laser and be able to turn on a second LED and so on.
To cycle through all the lasers, you can use two FOR loops. In the end we might have you change them to IF statements, but for now FOR loops will work.
for(byte col = 0; col < 4; col++)
{
for(byte row = 0; row < 4; row++)
{
if( laser_C[ col ] == LOW && laser_R[ row] == LOW)
{
//LED @ (col, row) = HIGH
// You can latch them on and off here too.
}
}// end of row for loop
}//end of col for loop
You might need a delay or a line of code that checks to see if the lasers are continuously being block, and so to ignore them until their states change.
In your other thread, you said your lasers were dimming. Did you go back and read the response I gave you, to fix that?