TempData is a bucket where you can dump data that is only needed for the following request. That is, anything you put into TempData is discarded after the next request completes. This is useful for one-time messages, such as form validation errors. The important thing to take note of here is that this applies to the next request in the session, so that request can potentially happen in a different browser window or tab.
To answer your specific question: there's no right way to use it. It's all up to usability and convenience. If it works, makes sense and others are understanding it relatively easy, it's good. In your particular case, the passing of a parameter this way is fine, but it's strange that you need to do that (code smell?). I'd rather keep a value like this in resources (if it's a resource) or in the database (if it's a persistent value). From your usage, it seems like a resource, since you're using it for the page title.
Hope this helps.