No, no. The "retcon" didn't change anything. It's only for those who payed attention to past lore panels outside of the game. Nothing literally changed. Originally, umbral/darkness was associated with stillness and astral/light is associated with activity and life, that's found in the lore book probably or from Koji Fox's mouth. None of those concepts are ever brought up or used in-game until shadowbringers. Without establishing or even incorporating the mechanics beforehand, it absolutely made no difference what the definition of astral or umbral were other than they were one of the sides of polarity of any element. There wasn't any real plot twist when they finally established the physics of light and darkness for the first time in shadowbringer. Hydaelyn is finally defined as the goddess of stasis, but that's still literally the Light theme. The one with the newly defined definition of darkness is activity, it's still the god of Darkness affinity. Light crystals and dark crystals enemies are present in Occult Crescent, the latest content and they don't have switched visual themes. Ice being stated to be the element closest to Light is from the raid in Shadowbringers , yeah, obviously the story beats from the expansion that introduces the definition of astral and umbral for the first time is going to be in sync with the new narrative information. But it doesn't mean ice element is astral only. All the elements can have astral polarity as umbral polarity. That hasn't been retconmed out. Black Mage still has Umbral Ice after all (with zero explanation as to what that means, of course). It's just stated by Ryne who grew up education less so she can cosplay as Hydaelyn. That whole raid is constructed from her imagination where anything can happen, so I wouldn't really use that a source for anything
And true, Koji Fox did say the 7th umbral was the calamity of all the elements. But I don't think he ever said it was astral, but that's probably what he meant and what we all assumed. But again. It's never stated in the game. In Shadowbringers, they clarify visually it's the calamity of darkness. In the Exarch's house, you can clearly see the seventh reflection to collapse has darkness color themes going on. But it never contradicted what Koji said. It's still all the elements but this time it's umbral polarity. But since no one said what polarity was the 7th umbral, and there's no visual guide in existence before Shadowbringers, there's nothing to contradict