I agree with what you're saying; it would be a good idea to have a couple of moderators dedicated to reviewing and approving these messages. Currently, as far as I understand, only the staff can do it, and they're already overwhelmed with work without having to review comments.
The creator of a project is supposed to be able to act as a moderator of their own page (and approve pending messages on their page), but it seems that Itch doesn't notify them when they have messages awaiting approval. Unless you manually go to the moderation menu, you won't know, and I think that contributes significantly to the problem of many messages remaining hidden for months