There is a way to track it, yes.
As you discovered, Neuro's escape date tracks progress to one ending (the "Paranoia" ending). Conquest tracks the the sum of the progress to two endings: the Paranoid ending, and the ending you're missing. So, progress = conquest MINUS escape date.
Another way to think of it is like this: how low can you get the conquest bar WITHOUT changing when Neuro escapes?