I guess if the 1917 icon of the Theotokos enthroned can be miraculously created by God as a non canonical icon, then so can the Virgen de Guadalupe. He makes the rules, He can break them if He wants to.
So we could say the Virgen de Guadalupe is a specific type of icon all its own and its features are not to be transferred to other icons. It quite simply is what it is.
False analogy. The Derzhavnaya
which Irish Hermit referred to was an old, existing icon painted a good century or more before its rediscovery in 1917. Olifa, the traditional oil varnish used for icons, darkens with time, the darkening accelerating in the presence of soot and vapor given off by oil lamps and candlAfter about 50 years, the appearance is usually still recognizable, but noticeably darkened. After a century or two, many icons are almost black. It was common practice for blackened icons to be repainted over the top of the existing image; the new icon may or may not have borne the same subject matter as the original. Repeated overpaintings were common, so that a board which might have been painted in, say, the 16th century, might have been repainted three or four times by the twentieth century.
The time of the painting of the Derzhavnaya
coincided with the height of the naturalistic, Synodal/Academic style which had all but obliterated traditional iconography. It is what it is, and I have never said that it is, in itself, uncanonical (there are many variants of the Mother of God Enthroned type), though the motif of God the Father in it is still problematic. However, it seems that God chose to use this imperfect vessel at that particular point in time to manifest His presence.
OTOH, the Guadalupe image remains outside Orthodox tradition. It never was part of it, and is highly unlikely it ever will be. This status has nothing at all to do with "Eastern culture". I make no apologies for saying this.