Apparently, the rating body is only able to accommodate game publishers’ confidentiality requests while submitted games are undergoing review. The moment a decision is reached (whether it be an approved rating or rejection), the GRAC is legally obligated, without exception, to make it public through its official website and the digital government gazette.
If you think you’re on the borderline between the local equivalents of M and T, and are willing to revise your content to get a more marketable rating, maybe you submit early? I know that’s a thing for movies in the US, as PG-13 movies can attract a broader audience than R. If the ratings board isn’t looking at the final product, though, can they rate it correctly?