I would think, that you point to enough discrepancies between Mantegna Tarocchi e-series motif and the actual poem.
From this it seems (at least to me), that Lazzarelli hadn't the pictures, when he wrote the poem. Or he got them during the time, when he worked on the poem with some text already ready and other parts unfinished. And he hadn't possibly too much influence on his "Apelles".
In my post I emphasized the discrepancies. But many other parts fit the cards precisely. There are two possibilities (1) He has the pictures, or at least something very much like them, in front of him while he is writing, which the reader sees as well. Or (2) He's describing what he wants in the pictures, and his own illuminator, as well as the printer's engraver, for some reason don't follow Lazarelli's instructions precisely. You are opting for (2); I prefer (1).
So let's look at his description of Venus, taking into account both the correspondences and the discrpancies. Here's the part that corresponds exactly
719ff. Nude Venus swims forth from the midst of the natal wave of the sea, and the fair one holds a sea-shell in her right hand. For she divests lovers from extraordinary cares and affairs. Nude Venus calls nude bodies to herself Indeed. the sea shell engages itself in sexual union within its own body. Passionate love is ship-wrecked by a sea of troubles. 725 The victor stands with his quiver of arrows, and he is swift on his wings. The nude boy Cupid stands with eyes covered...
Then he moves on to describe the Graces, where his description does not correspond to the card. (I have not found e a reproduction of the illumination, unfortunately; all I have is the "Mantegna" engraving.) That part, where Lazarelli describes them with arms entwined, and as seducers and entrappers of men, I quoted already.
If option (2) is correct, why did the engraver not follow Lazarelli's portayal of the Graces? The problem is that it would have been easier to follow Lazarelli than to make up something else, because Lazarelli is just giving the standard depiction, or three girls with entwined arms. The discrepancy requires an explanation.
If option (1) is correct, why did the designer of the engraving not follow the standard description of the Graces? One explanation might be that he had just done a "Huntsman and Three Nymphs" and liked what he did. It was easier for him just to repeat that scene. The Graces on the "Mantegna" Venus card in fact look very much like three shy girls bathing who have just been discovered by a huntsman. Or for some other reason the designer of the card thought the Graces should be portrayed that way. On option (1) (where the "Mantegna" comes first) the card-designer actually doesn't have to have a reason for departing from Lazarelli; he's probably never heard of him. In that case, Lazarelli, coming afterwards, is reacting to that portrayal by saying that it is not the way it should be done.
You could perhaps offer a similar explanation for why, in option (2) Lazarelli's illuminator or Sweynheim's engraver preferred a different way of showing the Graces--except that you have no such drawing, engraving, or painting to post from Sweynheim's circle in Rome, or from an engraver he might have hired. (We know it wasn't Zoppo, if only because he died in Venice,1478, and so couldn't have done the maps.) In fact, from what you have posted, we don't know whether Sweynheim's shop even did engravings, besides the one series of maps. Conceivably this hypothesized engraver could have taken the nymphs from some "Acteon and Diana" that was around. I don't know of any with a similar composition, but why would he have used such a scene, of maidens who wanted not to be seen by men, when Lazarelli clearly specifies the opposite? I don't know of other examples of hunters coming upon naked nymphs; perhaps you know some that would have been current in Rome of the 1470s.
I will give a few more examples. For the Sun, Lazarelli describes the detail of Phaeton and the Scorpio. The Scorpio is an unusual detail, not found on many depictions of the fall of Phaeton. Sure enough, the "Mantegna" includes the Scorpio. So, you say, the engraver got it from Lazarelli. But that is not necessary; the scorpion's role in the Phaeton story was well known and also appeared in artists' depictions. Here is a Florentine cassoni which Schuebring dated to about 1450. I apologize for the blurry image: I was photographing pages quickly at the Getty Library in Los Angeles and didn't realize I would be using this one.
And there is another difficulty: Lazarelli's illuminator omitted the comparable detail for Luna, which was also well known and he could just as easily have put in. So does the "Mantegna," strongly suggesting that the illuminator was following the "Mantegna" engraving and not Lazarelli's poem. I will explain.
For the Moon, Lazarelli mentions that her chariot is shaped like a ship. and that there is a Cancer in front of it. These are nice specifications, not that unexpected, given Luna's connection to the sea. Here is an example, the top of an early 1460's Florentine engraving, the "Luna" of Baldini's "Planets" series. It even has the horns that he wanted Luna to have.
In Lazarelli's manuscript, as in the "Mantegna," there is not only no horned Venus, but there is no Cancer either. If option (2) is correct, and the illuminator and engraver are following Lazarelli, there should be one. A crab or crayfish is as hard or easy to draw as a scorpion.
If option (1) is correct, no explanation is needed. The reasons for the Scorpio and the Cancer are quite different: one pertains to the Phaeton story, of how the scorpion came to the chariot and scared Phaeton, causing him to lose control (http://en.wikipedia.org/wiki/Scorpius
); the other has to do with the astrological association between the Moon and water and the observed association between the Moon and the tides. But It is not part of any dramatic event involving the chariot of the Moon, so the designer didn't think of it. Lazarellli, viewing the two pictures he bought in Venice, sees an asymmetry between them and has a suggestion for improvement.
You might reply: well, Lazarelli's illuminator used some of Lazarelli's original ideas, rejected others at his whim, and inserted his own non-standard ideas on occasion (like Jupiter's rainbow, which isn't in Lazarelli nor the standard portrayal of Jupiter, which usually shows Ganymede); what goes in the illumination is his prerogative as an artist. By the time Lazarelli sees the manuscript, it will be too late. Well, such an illuminator wouldn't get many more commissions!
But let us assume such a willful illuminator, and go on to look at Lazarelli's description of Apollo. Here it is clear that he is asking the reader to look at the image we see in the "Mantegna," because he's disgusted by its poverty. And this is as true of illumination in Lazarelli's own manuscript as of the "Mantegna" image. All Apollo has is a crown (and why that, instead of his customary laurel wreath? Lazarelli wonders) and a laurel staff. But what about his lyre?. What is the leader of the Muses doing without his lyre, on which he accompanied his singing the time he bested Marsyas? But at this point in his writing, he realizes that his illuminator isn't going to make any but the easiest of changes; so he just laments.
...Thus you are considered delightful when you sing on the resounding lyre, 0 beloved Apollo. It stands near a mirror for either your beloved son the Epidaurian is said to have invented this, or because you know future things in your mind and you see all times as if in a mirror. But maybe it has been taken from you and you do not pluck the lyre, 0 Apollo, but you mark out the earth and the golden stars with your staff. Not the laurel but the royal crown binds your hair, and the odorous laurel wreath fills your holy hand.
Well, there is no laurel wreath in his hand, just a laurel staff, in both the "Mantegna" and Lazarelli's manuscript. The bit about the "mirror" that Lazarelli thinks Apollo should see himself in is rather obscure; perhaps it refers to an epigram by Martial *Labahn et al, Wonders Never Cease
, p. 26 note 12, in Google Books). But let us go on. Lazarelli then recalls other noble attributes of his god, and laments some more, in the part I already quoted. (A "plectra" is a pick for plucking strings)
73ff. Now I remember that I have seen you elsewhere bearing bow and quivers, sweet plectra and the lyre. The Penean virgin was washing her shining hair. Youths were present and cheeks without blemish. I saw you, Delphicus, among the Hyperborean griffins. I knew you beforehand. The crow was near you. Who changed your culture? Who changed the mark of honour of your brow? Perhaps I am not permitted to know everything.
On Option 2 here, we have to suppose that Lazarelli was asking his illuminator to put in an inappropriate image, that didn't capture the spirit of Apollo (it in fact was used later, according to Zucker, as the model for depicting a saint!) and didn't characterize him as the leader of the Muses, just so that Lazarelli could express his lament. "Put in a crown and a laurel staff, but be sure not to include a lyre, a bow, etc." he is saying, in effect, on that option. But why would Lazarelli give such an instruction? And why would Sweynheim include, in a set he hopes to sell, an engraving that his text says is wrong (and actually is pretty stupid)?
Option (1) makes far more sense: Lazarelli has before him a picture of Apollo that he finds weak and impoverished, in a set of images purporting to be those of classical mythology, a set that artists in Ferrara are even using as models for their own images, and he wants Borso to know about it.
It is the same for Musica and Poesia, although conveyed by innuendo rather than outright statement. On option (2) we have Lazarelli instructing the illuminator to depict as puffing on a flute someone most glorious for her singing, and another most glorious for her stirring words. Why would Lazarelli instruct his illuminator to draw Musica and Poesia so inappropriately? It makes no sense. He is criticizing someone else's inappropriate depictions. And again for the Muses, he is clearly unhappy that all but two have been depicted as playing musical instruments instead of speaking or singing. If so, why instruct his illuminator to draw them with instruments, as he clearly specifies in the quotes I gave? Again, he is criticizing something done already, not proposing something inappropriate so he can express his regret at the result.