Wiki Redirects area lists 0 pages because it probably contains 0 pages. Synonyms are not pages. If you want to show synonyms by default in that area, you will need to change the area settings so that the default content-type filter is set to Synonyms instead of Pages.
If the redirects area is a sub-area of the System area, then the permissions might be inherited. In this case, you would need to implement custom permissions in the Wiki Redirects area.