I am aware that, on paper and in theory, this modus operandi is already in place, but it seems evident to me that (as you yourself confirm with your experience) it isn’t working properly and a lot, perhaps too much, still manages to slip through and get indexed/published.
The issue of an understaffed team seems so obvious to me that there is no need to reiterate it further. Given the massive amount of content currently available and continuously being added, expanding the staff to the extent required for the necessary manual checks isn’t economically viable. Therefore, the best approach would be to put greater friction and automated entry barriers in place.
This would then allow for a prompt response, which is critically needed in these circumstances, to reports such as the one I brought up regarding child pornography content. Such content should be removed immediately, the associated account permanently banned, and, if appropriate, reported to the relevant authorities as well.