uhmmm...can you show how that interview directly contradicts the other translations?
Namine isn't composed the same way roxas is. and again, i call it both master eraqus and terra's nobody because although it belongs to master eraqus, it actually belongs to a heart (master eraqus) that is connected to another (terra's). again, Roxas is a perfect example and why he fained in castle oblivion.
no it's more technically master eraqus nobody, but since his heart is being harbored by terra. Also it's not even necessary for MX to attempt to release his heart, the point is, master eraqus heart is no longer in his body and soul.
I'm assuming nomura made this boss to explain the scene better. but not necessary to understand later on.
as for sign, heartstation is usually accurate, but as for the secret ending scene, no they aren't. i'm sure there is amore accurate cutscene, but not so sure right now