Ephemera fonts are not true revivals because they cannot be traced to printing types. They are created from usually incomplete alphabets of hand-drawn lettering designed for historically documented paper publications (lithographed posters, title pages, business stationery, etc.) commercial signage or logos for such diverse objects as automobiles, tools and appliances.
Great topic and a possible source for interesting “new” typefaces for the creative mind, though you are correct that these would not be true revivals. The cool thing is that the designer would be able to take full credit for the face and THP could position itself as a founder, much in the way that I would sell my Lipo and Rose Madder under the THP initiative.
Yes, ephemera examples offer super “starting points” for fonts offered by the THP Bazaar. It would be ideal to illustrate your response with specimens of your Lipo and Rose Marder fonts. Can you furnish links?