A civilization advanced enough to create lifelike robotic humans and other animals might well have the technology for terraforming.
What if the carving depicts the constellation Orion from a planet where four stars appear to form the belt of Orion?
Imagine, for example, that Westworld is located in a star system like Alpha Centauri. That's close enough that the constellations would look basically the same, while still being far enough away to shift the perspective slightly.
Now check out this picture of Orion.
The red dot right below the western end of Orion's belt is a star system called Sigma Orionis. Perhaps that's the fourth star in the belt when viewed from Westworld.
