Unable to block inappropriate add ons in marketplace for a child account without disabling completely

I have spent hours trying to put an age appropriate filter on my son's account in marketplace, or at the very least blocking inappropriate mods as they appear. Multiple threads online from parents trying to do the same. This needs fixing or made much clearer if available already. My son has seen pictures of horror mods that show up on his feed. I have no option but to turn off completely. Please can you fix this. At least an option to grey out the pictures or block mods from appearing in his feed or better still to have age ratings that filter at source.