You are free to add your own values that are only referenced by other values and not directly used by the game. I do this all the time. For example:
ThrusterForce = 800
ThrustIncreaseTime = { BaseValue=3; BuffType=Engine; BuffMode=Divide; }
ThrustRecoveryTime = 6
FuelUsage = 200
None of these are read directly by Cosmoteer, I just have them at the top of the file for convenience.