@TonyG I have debugged my implementation of backward reasoning and it decides the same 2,035,598 machines as you 
Hence, we satisfy the requirements of [Debate & Vote] Deciders’ validation process and I have re-applied the decider officially, there remain 1,538,624 to decide!
When time permits I will check that my decider can output the exact same dvf as you did for extra safety.
Thank you again for this contribution!