if you talk about Position in Level Details - this is not for landscape, but for actors in the level - this option does not move the actual landscape ( well, i tried and only my meshes were moved and the land stayed at the same place)
Position
Level offset from the zero world origin, stored as an integer 2D vector. All Actors in the level will be shifted by this value when the level is added to the world (becomes visible), and shifted back when the level is removed from the world (hidden).