Marvel didn't say anything, the screenwriter did.
Yeah they did:
Marvel Says Tilda Swinton’s Ancient One in Doctor Strange Is Celtic, Not Tibetan
Marvel fukked up because in the trailer Dr. Strange is clearly some place with a lot of Asians then the next scene is Tilda Swinton....who is supposed to be Celtic. Unless the trailer is cut weird they dropped the ball.
Fred.



at nitpicking the differences between the two pictures, when the picture
Guess it's too hard to just create a well done asian character?

but this is a Dara Molloy, a modern Celtic monk. Does his outfit look closer to what you posted, or what she's wearing in Dr. Strange?