Manual approval of new users by instance admin to prevent spam

On my instance I am confronted with scammer events with titles like "Find the best youtube marketing consultant in India" or "How to choose the best twitter marketer in India".

My Instance has open registration. So I/the instance moderators need a tool, to approve (events of) an actor/user/group before there events are published.

I can imagine the following workflow:

Case A) A users registers, creates an event. Instead of publishing it, the event may get assigned the status draft and an approval request is sent to instance moderators. In the instance settings I would like to configure that I want to approve the first <n> events.

Case B) A new group is created. If an approved user is member of that group, then set the group as approved and everything stays like it is. If a group has only unapproved members, then the workflow can be as in case A). Here I can imagine to have a separate setting for groups: configure that I want to approve the first <n> events of a group. But I am not sure if this is reasonable. Once a group is approved: all members of that group are approved (also new members, that join after the approval of the group)

Hence trusted/approved users lead to trusted/approved groups and vice versa.