Wouldn’t surprise me if the Japanese legal authorities just sorta looked-the-other-way. If their prosecutors started turning up embarrassing information they might have re-thought the wisdom of a trial.
The real issue is Nissan knew Ghosn’s financials and looked the other way until he became troublesome, after which they nuked him.
I’ve had to translate corporate litigation discovery of emails, etc. before and all Japanese execs hide funds just like Ghosn did.