Adding users directly to the Wiki Moderators usergroup does not actually give them any permissions. For a user in this special group to get any permission, they must be assigned a specific part of the wiki (or explicitly All parts) that you say they are allowed to moderate, then the permissions with apply to that selection. The "Wiki Moderators (Default)" usergroup defines the default permissions used when you create a new Moderator in the VaultWiki Admin Panel under Permissions > Moderators, and the permissions can then be customized for each user you add there.
If you want to give the users permissions regardless if they are defined as a moderator or not, you should use a different usergroup than the "Wiki Moderators (Default)" group in order to accomplish this.