If you use diodes on the main Super 70’s board, you would not use the optional DPDT board connected to A and B.
If you DO wish to use an optional DPDT wiring board, you would not place diodes on the main board. You would use any combination of diodes and/or LEDs you want on the DPDT wiring board and connect it to A and B. The photo shown on the Build Document is just an example of what you may want to try. The key word for the DPDT board in the diagram is “OPTIONAL”.
The build guides on this site offer suggestions on diode clipping options. I hope this helps.