Okay, so my name has been brought here and by some PMs so I enter the discussion.
The list of synonyms on the F4F variety list is just information Jon shares. He makes no assurance that this information is accurate. This was discussed at length years ago after I purchased Black Provence from Mr. Watts that had been sold as Black Ischia since it was listed as a synonym at F4F. It produced a fruit with a light pulp although now that I have a strong population of wasps in the area it is usually (not always) red.
Jon lists source for his information. The Black Ischia synonyms shown came from Ray Givens. An archived copy of Givens' information is at http://figs4fun.com/links/FigLink006e.pdf At the same time, the F4F variety listing for Ischia Black does not list these synonyms.
Jon has several accessions of Black Ischia, etc. They are not all the same. The AD accession definitely is not the same as what is held at USDA Wolfskill and is believed by some to be the same as VdB (I do not grow this accession). New England Gardener (Tom Clery) sold Black Ischia that he got from USDA as well as from Encanto. He does not post much here other than to share his videos but, as I recall, at one time he said that he was not sure which of his trees was from Davis and which was from Encanto but he apparently got that cleared up. A few years ago he sold one tree of each and I purchased them both and they do appear to be the same to me. But, again, it is important to know what accession you are talking about when you refer to Jon's Black Ishcia.
Here is an old discussion that demonstrates the uncertainty with some accessions: http://figs4funforum.websitetoolbox.com/post?id=5114507