The Moth don't know exactly what sort of technology they have been trying to steal from Lyrgris. Their foreign technology people know the things they are taking are machines, but not exactly what they are or what they do. They have, actually, been dismantling and moving to the surface some of the components of the defense and shielding system. Though they have scanned the planet thoroughly and have found many of the machines spaces, what those machines do in those spaces is a mystery to them,
So, no, the Moth simply know the planet is inactive, and that its machines are up for grabs. But what those machines do? Nope.
So the movements of Charlie and company beneath the surface have no immediate meaning to the Moth. They suspect that whatever is going on will not be good for them, but that's all they have, a suspicion.
Consider this: if our people, in 1950, say, with your basic WWII-era tech, stumbled on a place full of 2020 human electronics technology, they might suspect what some of it does, but they really would be guessing about everything. A technician versed in the vacuum-tube technology of 1950 would be LOST looking at today's integrated microelectronics. It would take years of study for them to catch up and understand what they had. And this is only a 70-year gap between the one era and the other!
Now let's change that to the Moth finding all this stuff on Lyrgris that are the products of a technology thousands of years ahead of theirs. The difference in knowledge levels is so extreme as to make the Madracorn's devices unrecognizable in function.