Don't know if this is the 'correct' way to pitch something of the sort, but whatever. I saw a thread in the 'Lost Media' subforum discussing things that were found before the Wiki's creation; this seems like a great idea in my opinion. I know a while ago Dycaite removed the Nazi-related Simpsons gag, but I asked him about it a few weeks ago and iirc he said that it was fine to re-add. I think before an effort to writing these articles is done, however, it might be a good idea to add a 'pre-LMW' category to help organize and separate these from others. Notable examples include the aforementioned Simpsons audio, and 'Super Hornio Brothers'.
I'd also like to suggest the 'Historical' tag, for pieces of lost media that had large / community wide search efforts. Some examples come to mind, like Cracks, ADWSS, and Cry Baby Lane. They don't even need to be found, just ones that had a large search effort (Clockman). The more specific guidelines could be further expanded, this is just me spitballing. This tag would be a good way to show how the community can band together, successful or not.