Who are the builders in Kotor?

The Rakata (also known as the Builders) were a humanoid species with distinctive amphibian features. They were a technologically advanced race that developed early in galactic history, even developing some early hyperdrive technology.

Is Exegol the Star Forge?

Reddit user Luy22 suggest the Sith Citadel, the looming castle on Exegol where Palpatine was apparently hiding all this time, is actually a Star Forge, the ancient Sith automated shipyard created 30,000 years before the events of the original trilogy in the non-canonical Star Wars Extended Universe.