Tabby's Star is not in-game, because prior to 2015 when the anomaly was detected, there was nothing to distinguish KIC 8462852 from any other remote, real-world star, most of which have also not been incorporated into the game.
We could do what we did with TRAPPIST-1, and find a procedurally-generated star that just happens to be about the right type, distance and position and unilaterally declare it to be Tabby's Star.
Doing this, of course, won't create whatever weirdness is happening in Tabby's Star for you to go and look at. A substitute would be a perfectly ordinary, mundane star system.