It will always show the direction as a straight line to the nearest aether current. If you get closer to a different current while moving towards it, it will then show that one instead, so be warned. For my part, regular checking of the maps and a little common sense are all it took to find all the aether currents so far.

I've mapped The Sea of Clouds, Coerthas Western Highlands, The Dravanian Forelands and the Churning Mists. The former was the only frustrating one since I started that one first and it was the last one I could complete