Hm... Very interesting news that is...
Just based on Intuition and my thoughts when I heard the UA audio for the first time :
- to me it sounded like it was mimicing our own Discovery Scanner "honks"
Since we can carry it for a while in our Ships, I would assume it could either :
- act as some form of amplifier
- act as a filter for another "wavelength"
--> effectively allowing a carrier honking a Discovery Scanner to discover stuff that our own equipment all by itself would simply not pick up
Now knowing if that Option hasn't been extensively tested already in Unexplored Systems (I heard Ammonia or colder-than-ours Worlds have been checked in "Atmospheric tossing"), hard to say if I'm way off with that.
But given the corrosive nature - whatever one was to do with it shouldn't require too far travel, as there's simply the physical limitation of the reduced endurance of the Carrier (even when tossing it around in a Wing - there's just so much one could do).
Yeah, I'm too brain-dead tonight to give it much thought, but my impression was it was something "simple" we have missed. Whether that is in the sound, or something visible on the artifact itself, or something star system-related I am not sure. Those would seem to be the three main categories (if you include mission possibilities with system).
They supposedly cleaned up/changed the sound slightly in 1.3 - why? To make it more identifiable?
Edit: Also, on your last point re range to a possibly connected system, if the UAs only appear in specific systems (as opposed to procedurally generated in any SSS in any system), then we should be able to narrow this down to a "bubble" based on the max distance you could carry the thing from the systems it appears in before it eats its way out. Any takers on determining that distance?
Also, do we have a definitive list of all the systems they have been found in to date? And secondarily, systems they have been taken to?
I suppose honking one of each type of disco scanner at a UA might be a simple and quick thing to try, once someone finds another UA of course

And there does seem to be a similarity between certain sounds from the UA and a targetted scanner, so that might be something to add into the mix of Things To try ...
I _think_ people have done this (they have done just about everything else with the darn things). Somewhere there is a thread that was tracking all the different "test results", can't find it now - it may (or may not) be linked off the first page of this thread somewhere.