• Throttle %
• Control surface deflection
• Derivatives of various quantities
• Stage available resources

I've added AoS, AoD, ∆v, drag loss, steering loss, gravity loss but now the UI looks like it needs an overhaul, we're running out of colors and space.

Derivatives would certainly be good for the drag/steering/gravity loss.

Probably the FR needs to have a UX that looks a bit more like the custom window editor, so you'd add fields to it from a drop down, and then the colors would get allocated sequentially, rather than being tied to a specific value (then it definitely needs to save your work, and for bonus points save presets).