If you unlock the portal stones in an unintended manner, it seems that the Inheritor of Idols get stuck in your journal, and you can never finish it nor gain the Way Walker title.
Specifically what I did was that I unlocked the one in the Wayfort, and then I just plain forgot to unlock the Hawkethorne one. Next one I unlocked was Foothills, which then leaves two open, unconnected portals. When I unlocked the Hawkethrone one upon returning to town, it connected the three portals but did not finish the quest, and as far as I can see there's no way to do so now.
Specifically what I did was that I unlocked the one in the Wayfort, and then I just plain forgot to unlock the Hawkethorne one. Next one I unlocked was Foothills, which then leaves two open, unconnected portals. When I unlocked the Hawkethrone one upon returning to town, it connected the three portals but did not finish the quest, and as far as I can see there's no way to do so now.