Very cheap set of 4 unusual 1520 altar piece wings, or 19th century pastiches?

Auxerre enchères, from France, sells a "German School, ca. 1520" set of four scnes from the early life of Christ, with four saints on the back. Sized 95 by 47 cm each, they are together estimated at 3,000 to 4,000 Euro.

I have been looking on and off at these for some weeks now, and haven't yet found anything comparable. My gut instinct tells me these are 19th century works, probably worth the estimate anyway but very incorrectly described.

If, however, these are really from about 1520, then the estimate is way too low. So I'm puzzled both at the works themselves and by the description and estimate. The description is done by the respectable Cabinet Turquin, who do many attributions for smaller French auction house (i.e. everything but Drouot), and usually do a good job.

For starters, the works don't seem German to me. The saints have French names, not German ones, like the above St. Grégoire.
The other three are Hieronisme, Ambroise and Augustin, i.e. four of the major church fathers (Gregory, Jerome, Ambrose and Augustinus). These are the outer sides of the wings, the sides usually visible when the polyptych is closed.

The inner wings show the presentation in the temple, the annunciation, the nativity and the adoration of the shepherds. They are painted in a highly unusual colour pattern, gold and white with a few touches of colour only. I have not been able to find any other triptych or polyptych with these colours or anything resembling it.

Something big (at least 1 by 1 meter) must have formed the central panel here (assuming that these four were the only wings, and we aren't missing a lot ot of other panels as in e.g. the Ghent Altarpiece). While I have no evidence to support this, I would expect the central piece to be not a painting, but a wooden relief, creating a retable from perhaps Antwerp (the center of this kind of artworks in this period).

The paintings are not of the highest artistic quality, it is not as if some unknown masterpiece is being discovered here; but even so finding four wings from this period and in this style would be quite an interesting and valuable thing.

The main reason is that the wood carvings of these retables often have the same colour effect as these paintings.

The end result is normally something like the above, with painted wings and carved central panels. Note how the carved panels have superficially the same effect as the painted panels for sale here: largely brown or gold, with white accents for flesh parts. See also how the retables have four wings at the bottom, again similar to what we have here.

I have looked through the catalogue of the 1993 Antwerp exhibition of such retables, but I haven't found any with gold-painted wings though.

UPDATE: sold for 16,500 Euro, four times the high estimate!