'Madonna of the Pear' or 'Virgin and child with a pear', by Albrecht Dürer, painted in 1512. It is held by the Kunsthistorisches Museum in Vienna (under the title 'Maria mit Kind'), and there is no trace of it ever belonging to Getty's collection ("acquired in 1600 by Emperor Rudolf II (?); in the Treasury 1748").
Its "disputed provenance", as mentioned in the film, therefore, is a fabrication.
As for the other paintings:
The Getty Collection can be browsed online, but it might not contain all of the artworks the family has obtained, as many are probably held privately.
For most artworks that are on public display current ownership can easily be obtained, though.
The filming location of All the Money in the World with the most artworks is Hatfield House, in Hertfordshire, England. There is a catalogue available of their inventory of paintings and sculptures, but it is inaccessible online. It would shed a whole lot of light on the artworks that get little attention in the film - which, despite my eagerness to identify, are completely trivial to the interpretation of the film.
Additionally, it demonstrates how most of those artworks we see in the background are not part of the Getty collection, but privately owned by the current marquess of Salisbury. Moreover, having to move so many invaluable ("priceless") artworks around would have been unnecessary risky and costly.
The (disputed) Vermeer was his 'Girl with a Flute', 1665-1670, donated by Joseph E. Widener - along with the rest of his art collection - to the National Gallery of Art, Washington, D.C., in 1939, where it still is.
A depiction of the earthly paradise with Adam and Eve hangs in one of Getty's rooms: it's Maerten de Vos' 'Garden of Eden' from the second half of the 16th century. It was sold in 2003 through Sotheby's by an anonymous seller.
This was filmed in Hatfield House, and is indubitably part of their collection.
An obvious Mark Rothko, although I wasn't able to find an exact match (the lower right corner of the dark area has a characteristic 'droop'). This ('Untitled (Black and Orange on Red)', 1962), this ('Untitled (Green and Tangerine on Red)', mid 1950's), and this ('Untitled (Black, Red over Black on Red)', 1964) are similar works. The public Getty collection doesn't list any Rothko. It was likely part of the filming location.
This is most likely one of the several 'Portrait of Eleanora of Toledo''s that Agnolo Bronzino painted (+/- 1545-1560). I found only one instance of what is most likely the painting as seen in the film, but it is on a wikigallery page: a commercial website seemingly using Wikipedia's public domain library to present and link through to painted copies of these artworks. It can also be a copy after one of Bronzino's portraits.
As for the works I was unable to identify (LRTB), they include a 16th/17th century painting of a reclining Venus with Cupid; a full portrait of a standing man (18th c.); a full portrait of a woman in a chair (I think by a 20th century female artist - I recognize it, but cannot remember the name); an English or, more likely, Dutch landscape or view on a city, reminiscent of Van Ruysdael's paintings; a (late northern medieval?) portrait of a woman; a neoclassicist or baroque mythological or biblical scene; a portrait, possibly by Rembrandt; a landscape with what appears to be a bridge or a fallen tree; a portrait of a woman, possibly Judith (Peter Lely, Willem Wissing?); and another landscape.
Now I need to get my hands on one of those catalogues..
