Window comparator diode direction
It won't work at all in this case. The output of the opamp goes high, and the diodes turn on when the output goes high. The diodes are in an "or" configuration allowing either of the comparators to pull the 4049 high (towards 5V). 

If the diodes were reversed, very little current would flow and the circuit would not function as intended and the input of the 4049 would always remain low.