I re-read the text, and unless I'm missing something, I do not see any prohibitions against players using the Aid action against a DC 15 (the default) to help a puzzle solver with the ring-lock thing in C4. Anything I'm missing here for rules-as-written playtest purposes? Looks like if you have a party of four, they could all work together to get up to a +6 to the Skill check to disable the lock, making it MUCH easier.
If they get the gemes, you're looking at an effectively +5 to +11 to disable each DC25 mechanism.
Yeah, I think it makes sense for folks to be able to offer helpful insight into navigation. It also makes sense for someone bad at it to give bad directions and screw it up.
What is a little weird is if two players succeed on aid and one critically fails, I think the two +2 bonuses simply cancel out the one -2 penalty for a net zero, since the bonuses don't stack. I'd welcome being proven wrong there though.