Neither version of the story really checks out.
1) A bookie allowed an interpreter to rack up a 4.5M debt for some reason and then Ohtani was good enough to pay it off, but realized that was illegal and then lied about it.
2) The interpreter had access to 4.5M of Ohtani's cash, stole it, gambled on it, and Ohtani only learned about this after laughing it up with his pal after yesterday's game.