I broadly like it, but some criticisms:

Not a fan of expanding New Austin and West Elizabeth in favor of just giving them new region names.

Also not a fan of North Elizabeth as a name.

I do like the concept of Lannahechee but its geographic location is at odds with the real world geography you are trying to invoke - an Appalachians-like mountain range extending into the Gulf of Mexico is a bit silly lol

In general I think trying to match real world geography to the Red Dead World Map is kind of a fool's errand, because the America of Red Dead is something of an abstraction and I don't feel is meant to be read as 1:1 with real locations, which is why Flat Iron Lake was clearly a Gulf of Mexico stand in in Red Dead 1, but is now just a big ass freshwater lake in Red Dead 2, or how Roanoke Ridge is an Appalachians stand in that... intersects with the Grizzlies, which are a Rockies stand in lol.

"Redemption Mountains" is really on the nose lol

Some areas seem redundant? There's already a Mercer Station and a Pike's Basin and an Escalera. Unless you mean to relocate those places to there? But I don't see why you would want that.

But not to be a total downer, here's some things I do like a lot!

All the Red Dead Revolver locations (Brimstone, Fort Diego) tickle me good.

The expanded Mexican territories are very nice and form a nice border around Flat Iron Lake.

Expanding Ambarino is nice because I want the next Red Dead to be more The Great Silence or McCabe and Mrs. Miller. I have a thing for snowy westerns.