Can't speak to Eberron (never got into it), but my understanding is that the history of the setting remained frozen at the same spot from 3e to now, and none of the setting details in the world changed, rather more detail has been added over the years.
There have been significant retcons to the Eberron setting literally every time it has gotten an edition update. For your own sake, I’m glad you aren’t an Eberron fan, because there’s no way you’d be able to handle all of the retcons. If the destruction of the Core in Ravenloft made you hate modern 5e, the inclusion of Baator in 4e Eberron would have given you a heart attack.
For an example, let’s take the Aasimar. Aasimar aren’t a major part of Eberron and were originally assumed to work as they did in the rest of the D&D Multiverse (being the child of an Angel and Human).
But then, still in 3E I believe, Keith Baker had a really cool idea on how to make Eberron’s Aasimar interesting and unique to the setting by merging them with the Yuan-Ti. The Shulassakar became Eberron’s Aasimar, they’re divine Yuan-Ti connected to the (mostly) extinct Couatls. They look like normal Yuan-Ti, but have feathers, psionic powers, and worship the Silver Flame. Some more powerful versions have Cleric magic and wings.
Then in 5e, Keith had another cool idea; tying Aasimar to different religions and planes of existence instead of specific divine ancestors. So now we have Aasimar that are the physical manifestations of the Silver Flame, Blood of Vol, the necrotic energies of Mabar, and so on. You can be a Seeker that believes so much in your own internal divinity that it awoke the divine spark in your soul and transformed you into a vampiric Aasimar. Or an emaciated High Elf Aasimar transformed by the collective faith of their people.
(I don’t know if or how Aasimar were integrated in 4e. Did 4e Eberron have Daevas?)
In my Eberron, Angels and other divine entities are too otherworldly and aloof to have children with mortals, so I chose to implement both 5e’s Exploring Eberron Aasimar and the Shulassakar. Hell, I ignore the Shulassakar’s canon rivalry with the Yuan-Ti and make it so they are the only Yuan-Ti on Eberron.
This is the benefit of not caring about canon or retcons. I get to choose the lore for any given species in my version of the setting regardless of the edition. Shulassakar haven’t appeared in 5e yet, but I think they’re cool and still use them. I think base D&D Aasimar are bland and uninspiring, so I make my own versions for my own game, usually using the base mechanics. Aasimar in my setting are xenophobic isolationists that think they’re better than everyone else because of their divine blood and build their cities in the irradiated ruins of an ancient empire (partially based on Fallout’s ghouls).
Lore is meant to inspire games, not to be the sacred texts everyone has to use for their games. Canon is a curse that often prevents new, imaginative versions of older lore in the name of tradition.
