You should definitely contact staff as editing/posting on the site by an 8-year-old is a ToU violation. If they are using registered accounts, they need to be blocked. If using an anon account, their IP needs to be removed from almost (I think) literally everywhere.
To clarify, by "staff", I mean payed employees of Wikia; as is the standard use of the term. I am not referring to local admins; which some wikis insist on calling staff.