One thing that occurred to me while rewatching the latest episode; SM-33 again uses the exact wording "
can't say as I recall any At Attin" and it got me wondering; is this just another quirk of having a space hamster eating his brain, or an indication that he's been programmed specifically to fane ignorance by the previous Captain? As in he literally
can't say. It would make sense that if a Pirate is going on a journey to the planet of eternal treasure with a crew that will 100% murder him to death and take all the loot for themselves, that he'd institute at least some security where the ship's droid is concerned.
It could end up being a simple matter of Fern just having to explicitly order him to recall the data.
If these planets are that old, they would likely not be in the Outer Rim. They might be in the Core, but that seems unlikely, so I would guess the Mid-Rim, which would have been the old Outer Rim a long, long time ago, when the Republic wasn't as large, and there may have been Sith Empires in the current Outer Rim and Unknown Regions.
It's honestly hard to say how far the Old Republic extended, but given that we know of several ancient Jedi and Sith worlds in the Outer Rim, I'd say it's a given that it stretched pretty far.
I think what people forget when they look at 2D maps of the Star Wars galaxy is the volume of 3D space, and it's one of the reasons why drawing borders on a star map is basically meaningless. The actual "borders" of an interstellar civilisation would look less like a terrestrial nation, and more like a model of a molecule's chemical structure; a cloud of tiny spheres denoting inhabited systems, with lines of safe travel routes connecting them and a whole lot of mostly empty space.
Even if the Old Republic was smaller than it's successor it terms of numbers; just because the Jedi and by extension the Republic has a presence on far flung worlds like Lothal, Ossus, Iilum, etc., doesn't mean that *everything* extending out that far has been settled, or even charted. It's a big galaxy after all, and it takes time to spread out from the major hyperlanes once they've been charted.
The Hydian Way for example goes from one side of the galaxy to the other; but that's like building a road through the middle of the Amazon, or the Sahara. You can travel back and forth along that road just fine and cover enormous distances in good time, but it doesn't make getting to anywhere even a few miles off that road any easier or quicker.
So I'd say they could be literally anywhere. They'd be just as hidden in the Core as they would in the Outer Rim, or the Unknown Regions.