The work in question is a Historia Angliae (a mythical history of England featuring Arthurian themes), its dedication illumination being of Galasso da Correggio offering the manuscript to Filippo Visconti, the miniature attributed to Giovanni Zenoni da Vaprio (BnF Lat 6041D). Different members of the Corregio family (namely a later painter) have been discussed here before, but this Galasso was a member of Filippo's privy council. The primary scholar researching this Galasso is Alessandra Malanca; e.g., see her “Le armi e le lettere: Galasso da Correggio, autore dell’Historia Anglie”, Italia medioevale e umanistica, 48, 2007: 1-57.
Information I was able to cobble together on-line (bad Italian translations follow): The lesser-known Galasso (ca. 1368-1442) fought for a long time to defend the autonomy of the Correggio domain from Filippo Maria Visconti, who, however, approached after 1420. The point of arrival of their reconciliation was the selection of Correggio to the committee (privy council?), commissioned in 1433 by the Duke of Milan in favor of Galasso and his brother Giberto. In the same years, probably in gratitude, Galasso dedicated a Historia Anglie to Filippo Maria, currently preserved by three manuscripts: Paris, Bibliothèque Nationale de France, lat. 6041 D (XV century); Palermo, Municipal Library, 2 Qq C 102 (XV century); Correggio, Municipal Library, ms. 33 (XVIII century). The work narrates in Latin prose the history of the first English sovereigns, going back to the roots of the Brittany material (Geoffrey of Monmouth and Gervasio di Tilbury) to try to extract from the Arthurian truth from the legend, in contrast with the fables spread thanks to fictional literature . The cultural portrait of Galasso that emerges is interesting: first a reader of French novels according to the lordly custom, then a scholar of the humanities, to whom he approached at a mature age, as his contacts with Pier Candido Decembrio and Francesco Oca also demonstrate.
From the Historical Archive of the Municipality of Correggio (at the Museum) one finds a document that dates very close to the Bianca and Sforza wedding, and is notarized in the town in which Bianca was raised, Abbiategrasso:
E, 242: 1441 October 26, Abbiategrasso. The Duke of Milan Filippo Maria Visconti, appointed his adviser Corradino da Vimercate as a prosecutor (surely appointed representative is meant here), sells to Galasso da Correggio the Castelnovo di Sotto with the villas of San Savino , Campegine, Meletole, Cogruzzo, Praticello and Fesso, for the price of twelve thousand florins.
It is tempting to link this purchase by an elite so close in time to the wedding as a wedding gift to the father (the landholdings perhaps bought at a premium), especially given the context of Abbiategrasso (Filippo in turn of course made a substantial dowry to Sforza; perhaps these were properties previously gifted to Bianca for an income and then exchanged once the much more substantial cities of Cremona and Pontremoli were given to her and Sforza?). We have a proposed date above of 1433 for the manuscript in connection with a reaffirmation of existing Correggio holdings; so that would mean the illumination preceded the CY (based on my assumption of it being tied to the October 1441 wedding) by a mere 8 years and might have served as a model on how to depict Filippo or at least a Visconti ruler (always idealized and never true to life, not in the CY nor in this illumination at all events). There is a loose resemblance between the kneeling Galasso and diminutive servant as well as the seated "Kings" in both the manuscript and the CY King of Cups, especially in the odd headdress (of course the dedication scene was very stereotypical). Also noteworthy is that Visconti is associated with the coin and cup/"grail" suits in the CY, thus this king of cups - albeit bearded - would signify his line (perhaps the bearded Gian Galeazzo, Filippo's predecessor) . Both works presented side by side below: