Too be fair, isn't it possible, seeing as how there appear to be two of them, that the two together would actually be powerful enough to penetrate Fausts magic?
Maybe alone they are strong enough to penetrate it.
Besides from that, if they aren't using the same magic that Faust uses ((Any sufficiently advanced being is indistinguishable from god, which is why the Collective refer to them as Extradimensional, Parasentient etc)) the magic wouldn't stop them.
Maybe they are actually there, but unseeable, untouchable, between worlds etc
There are thousands of ways they could be watching that circumvent Fausts protection