I used a fresh install of Alfresco 4.2.f using the installer.
1. Edit a wiki page and add a link like "[[Täst]]"
2. The link is shown in "red" to indicate the page does not exist.
4. Create the wiki page by clicking on the new link and adding some content.
5. Reopen original Wiki page.
6. Result: Link is still shown in red (expected behaviour: Link is shown in blue)