Magic Moon: The first part of your post was very difficult to read, due to problems translating from your Spanish into English. Are you writing in English, or in Spanish and then translating it using Google Translate? The latter would probably be better. You can also post in Spanish first and then offer a translation into English. That way, we can go back to your Spanish when we are puzzled by the English. I could guess that by "letter" you meant "card." I thought that "stick" would be "baton", but I am not sure. Sometimes it seems that you mean "suit". Other words I could not guess. There is also a problem with the prepositions. It seems to be a valuable contribution, perhaps suggesting ways of playing "VIII Imperadori" that I had not thought of - but I cannot understand the English!
I have no opinion about the "Imperatori" games after 1423, as far as how many superior cards they had. It may also be that the subjects became defined differently, more like those of Kaiserspiel. To me 1423 is enough. For the rest, it is relevant that Ferrara's 1434 decks were again imported from Florence, but the 1440s decks were made locally (see Pratesi at https://www.naibi.net/p/55-IMPER-Z-1OCR.pdf).
About the assignment to Alessandro Sforza, the chief argument has to do with the heraldic emblem on the shield. The argument is not conclusive, as the device was used by others, too, as you point out. This has been discussed in numerous posts on THF (search term "Alessandro") and articles in The Playing-Card and elsewhere. If you search "Alessandro" on the Ask Alexander" search engine, some good articles appear, in vol. 42, 44, 49, and 51. There are also articles in the books Il Mondo in Mano (reviewed by Depaulis in vol. 48), and Les Tarots Illumines. Here is a nice summary, by Pratesi in an August 2024 note I translated recently as "The Countess's embroidered trionfi", viewtopic.php?p=26584#p26584)
"Alessandro Sforza" is mainly just a convenient tag for talking about that set of cards. The youthfulness of the figure is not definitive of its date: if it is meant to commemorate his days of glory, he can be as he was then. They are mostly of interest as reflecting Florence of around 1450, probably by the workshop of Lo Scheggia, as Huck and I have said for many years, although art historians only recently. Likewise the attribution of the Rothschild cards to the Dal Ponte workshop is generally accepted now, the art historians give meager arguments if any. I think the best study is still mine, from 2014 with revisions up to 2017, at https://rothschildcards.blogspot.com/.It may be significant that the name Alessandro Sforza is used for the well-known Catania tarocchi, discussed by Thierry Depaulis, Emilia Maggio [note 2] and others. The motif of the ring with an intertwined flower that is the basis of the proposal has, however, been convincingly linked to Nicholas III of Ferrara, and therefore either the Pesaro attribution is rejected,[note 3] or it is considered ‒ as in a study that would limit the production of the deck to the period 1445-1468 ‒ that Alessandro was the only Sforza to have received that emblem from the Ferrarese court where he grew up.[note 4]
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2. For example E. Maggio, The Playing-Card, Vol. 44, No. 4 2016, pp. 256-268.
3. C. Dorsini, “Tarocchi rinascimentali fra Milano e Ferrara,” in S. Bonaccorsi and E. Maggio, editors, Il Mondo in Mano, [Ragusa] 2019, on p. 25.
4. S. Abele-Hipp, The Playing-Card, Vol. 49, No. 1, 2020, pp. 14-17.
In discussing the Visconti-Sforza deck in this context, I think it is important to disregard the 6 "second artist" cards. They are of a different time and style than the others, including the suit cards.
Since originally posting, I have added (now April 3) one additional sentence, in red.