Does seem like a weird choice of skill roll and the consequences for failure. "Following the Old Dwarf Road is not easy and a couple of times you find yourselves on the wrong track." Being unmarked and hard to follow is not what I expect from a major trade route. The Enemy Within talks about how trade with the Dwarves, Border Princes and Tilea have made Averheim relatively wealthy, so it's surprising that the road would be not just in disrepair, but hard to even see. You might change the roll on the first leg from Observation to something like Athletics or Resilience, and adjust the flavor-text to represent bad weather or poor road conditions instead of actually getting lost on a major highway.
What's really weird to me, though, is that the part of the journey on the road in part one is Observation vs 2 Purple, but then when they go overland hiking in part two it's Nature Lore vs 1 Purple. Since both use Intelligence, that's basically saying that going cross-country is actually easier than following the road. I'd be strongly inclined to swap the difficulties around, so the lower difficulty roll is used for the highway travel.
Edited by r_b_bergstrom, 23 July 2014 - 03:20 PM.