I like the idea in general, but tying the feature to the aether compass doesn't really make thematic sense. I'd rather just see it unlock as a regular action you could use, like the Dig action for treasure maps.

As a counter to the "would make it too easy" argument, there could be varying levels of effect tied to consumables. You could buy tracker's manuals with seals, effectively making it so you can make it easier but get less of a reward.

Basic action: "You sense that an elite mark is nearby." / "You do not sense that an elite mark is nearby." Message changes if the closest mark is within a certain range, say 500y.
Tracker's manual type 1 active: "You sense that an elite mark is (nearby / some distance away) to the (direction)."
Tracker's manual type 2 active: "You sense that (name of mark) is (distance) to the (direction)."