Vincent Waller has confirmed that the "missing" shorts do not exist
From The Lost Media Wiki
As it has been discussed on the LMW Forums, Vincent Waller, a writer for SpongeBob SquarePants, has reached out to LMW user Radiant Lloyd Firefly on Twitter that the "missing" shorts other than the ones that have been posted online do not exist.
Link to the Twitter thread where Vincent Waller replies to Radiant Lloyd Firefly.
I was wondering how to re-write the article with this new information by either putting it in "Found media" and "Pre-LMW" or "Non-existence confirmed" or possibly both.