Just thought i'd mention the first lightsabers were actually just a hilt with a cable going to a power pack on belt and they were around at 5000 years BBY the newer sabers as are commonly though of that have a power crystal in them to make them independently powered (not needing a powerpack and cable going to hilt on your belt) were invented about 4000-3000 years BBY their not actually sure when it was invented. However you are correct in the sense tthat the holograms from baefore the republic shouldnt have modern sabers they should have the ones with a powerpack on belt.
In my OP I did actually distinguish between protosabers (the ones with cables) and modern lightsabers. The holos in the game portray modern lightsabers.
Also, just so we are clear I was talking more about the holos than the statues which are supposed to be actual recordings.
As for it being an oversight. A Few years out I could understand. Even a few hundred. But, 20,000 years? That is a massive oversight!