Existence unconfirmed status

"Existence Unconfirmed" is for lost media which has been reported to exist by a secondhand source, but no concrete evidence it exists.
For example, the Kurt Cobain "Ren and Stimpy" song is unconfirmed as it has only been mentioned by one person and no other evidence supporting it's existence.

The Clockman cartoon was also classified as Existence Unconfirmed up until it was actually found. Previously, only the accounts of Commander Santa and Michael W. Howes and no official evidence of it existed.

On the contrary, the Wicked Witch episode of Sesame street may be lost,but it's existence was confirmed and backed up by official scripts and screenshots.

I hope this clears things up. So then, asking as someone deeply interested in the case, Yeah Yeah Beebiss II would be considered "lost, but confirmed" since there is evidence it exists but seemingly almost no way of finding it now.