Below is a further discussion on Crux before Royer, which is part of a booklet I've been working on for a while. This might give a better perspective to the question here...
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A recent found image of the Cross appear on a celestial globe that was engraved by Jodocus Hondius and created from drawings by M. Emerie Mollineux (Molyneux) of Lambeth in 1592 in Tudor England, whose
new constellation name was then adopted by Bayer in 1603. This clearly precedes Royer claim. By since this time the
stellar name of Crux has been found in several earlier historical references. One of the earliest significant known sources is from a private letter written in 1503 by the Italian navigator, Amerigo Vespucci, who described "
four magnificent stars" Another by the sailor Antonio Pigafetta in 1515 said while travelling of the Globe, wrote;
“...a wonderful cross, most glorious of all the constellations in the Heavens.”
Modern historians have more recently have assigned Crux's original derivation to the Italian, Andrea Corsali that was found in an old twenty-page letter and manuscript entitled; "
Lettera di Andrea Cosali allo illustrissomo Principe Duca de Medici, venuta Dellindis del mese di October nel XDXVI"; (The original of can be found in the National Library of Australia and is available in the Internet accessible
Archives Section.) Here we can clearly see the small drawn figure on the first written page of the manuscript clearly showing Crux and its five principal stars near the zenith, but also seen are the two Small and Large Magellanic Clouds and the position of the South Celestial Pole (polo anlatico). The whole page can be viewed by selecting the thumbnail mentioned in the page above. It seems this document is yet to be properly translated. Corsali wrote in 1516 that Crux was;
"...is so fair and beautiful that no other heavenly sign can compare to it."
One of the first instances of the Southern Cross in the historical literature was by Dante's (1265-1321) in the famous trilogy "
Paradisio", "
Inferno" and "
Purgatoio".
Here in the last book, Purgatio, he describes only the four principle southern stars of the Cross - naming them after the admirable virtues of
Justice,
Prudence,
Temperance and
Fortitude. Dante seems once to have seen the Cross low on the southern horizon and likely missed faint Epsilon Crucis in haze or poor seeing.
Yet of all of these claims it remains quite uncertain if these individuals had any influence with its popularist name of today. In my own opinion the true derivation of Crux's name and origin will likely to remain forever unknown to us.