It is simply a motion simulator to use test of the software. It is not meant to make a twin of a machine where it can mimic what output #1 does on your physical machine, etc... This is because it does not mimic any real motion plugin that runs real hardware.
I would say plugin developers use it more as a test bench comparison because the "simulator" (we call it just Sim) always does the right thing. So if there is a problem they are dealing with, they can look to see if the problem also exists with Sim. In that case, there may be something wrong inside Mach. But most of the time, Sim shows the developer that there is something wrong with the way their plugin is working. And if they can't figure it out, they get with me and we work it out. Sim is a litmus test, so to speak.
So to answer your question directly, there is no direct documentation with Sim. But it isn't too hard to figure what all it does by entering its configuration dialog. Every option it has is in there.
Steve