Right, that was more or less what I'd concluded -- landforms and landmarks are moved, then the compass placed where it can fit. It just confused me for a bit yesterday because the compass stands out so well and is easier to spot than, say, reading a landmark name or mapping how a forest changed shape. "Compass in top left, rotate CW, compass in... bottom left?! rotate CW, compass is top left, rotate CW, compass in refrigerator..." :)
Once I looked at the actual map contents, rather than decorator, it totally made sense. I could see what it was doing and had a guess as to why, but wasn't sure if it was deliberate. Sounds like it probably was, or at least not consciously avoided. I don't think it's wrong, though because I can see it changing some of the locations chosen surprised me (moved from 'in big water' [open sea] to 'in little water' [among islands]). Trivially fixed by manually moving it, of course.
Still really happy with the rotations! Thanks watabou!