We are actually still missing a large chunk of Coerthas from 1.0, although some of this area has been added back in as Pvp's Fields of Glory. Coerthas Eastern (and Central apparently) Lowlands are actually in between Coerthas Central Highlands and the Shroud. That's more likely to be the transition area. That zone line is skipping over a huge area of land. If you look at the 1.0 maps the current Shroud/Coerthas zone line is just odd.