Not sure if you're still around, but here I go!
The ghost does indeed always start with 1... d5, the queen's pawn as Black, no matter what you play. By using this constant variable, it is possible to manipulate the AI to play predictable variants. The best set up I've found so far involves using the Blackmar-Diemer gambit and following recorded variations. If not, I use Stockfish against it. Drago also uses the same opening as the ghost, so it's good for him as well.
I recently beat the entire game in under two hours if you are interested: https://www.speedrun.com/learn_chess
There is this Ghost, and can't get out of his castle because he's attached to the castle. I, the player need to get back his chess pieces, they were stolen by a pirate named Drago, The ghost teaches you how to play chess and once you completed his training he waits in a tournament room, and thats where you play against him. The game always starts off with a Queens Pawn Opening, I will attach pictures.