Reviewing through your description, you should be able to set multiple moderators via your instance's admin console >> permissions page. However, I always find the following section of documentation helpful in determining Who Moderates What?
However, if you are seeing a different behavior than what is outlined there I would recommend submitting a case in your customer group here in the Jive Community as a next step so that a member of our support team can investigate directly in your instance. When doing so if you could also provide the following information, it should assist with their investigation:
1. An example of the content you are wanting the user to moderate
2. The username of an account you are wanting to set up as a moderator of the content linked in #1