raxxla existed from day 1 in the game, if you believe braben. back then discovery scanning was infinite so if a stellar body was in the "system" then it would show up.The purpose of this is to see if there is anything to find way way out from entry point. Problem is, the further out you get, the bigger the area you havent checked becomes
The only way it would not is if raxxla was instead a POI. Since that would only appear within a certain range of it. Nobody's gonna stop you from wasting time but if you believe something is that far out and thus outside of the view of the system map, then such things could exist in any system, and it's position would be completely guesswork, giving you a sphere of searching that is physically impossibly too large to map.
If we also believe braben, and we must since we are assuming raxxla is in the game like he said, he also said there would be no hints or clues in the game as to where it is.
This implies that it's located somewhere not implied by anything noted in the game or books. Instead, it's just placed somewhere, likely without any rhyme or reason except that it is somehow accessible to players should they happen to find it and scan it in a way that would identify it as being special and probably raxxla. It's not meant to be found, except by random chance ....so 1 in a few hundreds of billion chance of crossing the planet that is raxxla, rather than a puzzle a smart person can figure out with the right clues.