Hadn't thought of it from this perspective. An untraceable signal coming from the moon would also be useful for military communications. Electronic warfare and signals intelligence have been powerful tools for both sides in the Ukraine-Russia war.

It's not that untraceable when you have satellites that could pick it up before the bounce.

I have no understanding of the physics involved, but could the broadcast location be reverse engineered? (With triangulation and clever math?)

Your location is very very visible to any plane or satellite passing overhead.

Indeed, though it would take some coordination to actually narrow it down precisely. You'd need a few different planes/satellites to detect the signal and share their reading to allow triangulation. With only a single plane or a single satellite that is not in geosynchronous orbit, you could take multiple readings and get a rough idea of location, but the inability to turn from a straight line (not impossible for a plane of course, but it would require intentionality and willingness for the crew/commanders and typically not cheap as it disrupts whatever flight plan they previously had) would be a hindrance. That said, with how many satellites are up there I doubt it would take much extra effort to do that coordination if the satellite operators have motivation to do so.

Highly directional antennas on a moving platform can perform effectively radio direction finding independently.

Let's remember that there is also a antenna array with LOS yo the mooon.....

The moon is visible to ?half? the earth at a time? That’s a huge search area. Certainly the antennas broadcasting to the moon are quite directional, and outside the main beam, would be hard to detect?

I don’t understand how? Wouldn’t the signal be highly directional? Surely it wouldn’t be easily detectable unless the viewer’s POV intersects the path of the beam?