Jester David
Hero
Natural change is usually accepted. Progress and evolution. The change of kings in Cormyr was pretty accepted. The natural flow of history. And new additions that fit the setting and work with the established lore.And, FR fans are extremely adverse to any setting changes, just like fans of pretty much anything with the D&D name on it. Tradition is very, very important.
When things get crazy or revolutionary instead of evolutionary, then people get upset.
Dragonlance and Forgotten Realms fans demonstrated massive changes aren't well accepted.
That was a reprint of a 2008's Pathfinder Chronicles Campaign Setting, updating it from 3.5.You mention the Inner Sea Guide - 2011 release there. So, what, three years into a setting that had zero background information? We're one year into 5e. Give it time. They'll get there eventually.
Since they'd only published a couple Adventure Paths and hadn't much expanded the world, the setting was pretty blank. So the tapped 26 authors - including a bunch of recent RPG Superstar finalists - and just kinda assigned people a place with a name and let them invent a nation.
The opposite of how you'd want to handle a FR setting with lots of lore and details.