Do you mean the original digital release of the music itself?
I think that’s pretty straightforward - you can update ‘Gaijin Games’ to the correct artist across all of them (which shouldn’t really meet any resistance). If you want to maintain the Gaijin Games credit, then put in the correct/specific artist, but leave ‘Gaijin Games’ in the ‘credited as’ field.
If you want the original release date of the game stored somewhere that’s trickier, and I just don’t think you’ll find consensus tbh. I wonder if it would be worth opening a new discussion re. that (if you’re really keen on it), and potentially suggesting a new relationship, fields or pseudo release type etc to handle a game or film release date + details etc.