If you have a bicolor LED that has 3 pins, the cathodes of the two LEDs are connected together internally and available as a common connection (middle pin). The other two legs of the LED are the anodes of the internal diodes.
The 3PDT footswitch is wired so that power is alternately applied to one of the anodes to light up the respective LED. A single current limiting resistor is used to set brightness and is shown as 10k ohms. Reduce the value to 4.7k or even 2.2k to make the indicator LEDs brighter.