Cartoon Network stopped using their old system to manage their video catalog and are now exclusively using the new video-data api, the same one as the mobile app.
This means that we can't juste "guess" the episodes IDs (which was just a number) since they now use hashes (long string of "random" chars that we can't just guess).
Until we can fully document all the new system, we can't be sure if there's a way to find "non-active" content.
CTOON's preview platform will be updated in March to support the app data but only for what we can actually see.
If you know how to get the new data or have some hints, feel free to drop me a tweet/DM (@sugrocks or @CTOONnet), send an email ([email protected]) or use Discord (Kody#1337).
Warning, SPOILERS ! Don't forget to add spoilers when you post images or links on 4chan, reddit or other places about a future episode.