This can only be edited from the Message Catalog Editor, which Blackbaud Luminate Support has access to. Please contact them for further assistance.

In addition, for closed events, you can input a URL redirect.
Such an edit can be made on the "Publish" step of the TeamRaiser configuration process:
  • Closed Event Redirect URL: Displays the page identified below when constituents click a link to an event that is closed or archived. (Note: If left blank, the system attempts to find the next active event before displaying the Page Not Found error message.)