The rock wall near the roads are indeed a real problem. Often the AI gets either stuck between them or they go off-road trying to reach their destination.
On the other hand, removing them would be a shame as they fit perfectly into the landscape. Maybe it would help already if they are moved away from the roads a little bit.
Sander just told me gently that once again my missions are crap.
Below downloads contain fixed versions of Cleansweep and Return the Tractor:
Cleansweep v1.01 - Fixed the missing notes and briefing text.
Return the Tractor v1.01 - Removed cwr2_abel in the list of required addons.
There is another little problem with "Seargant Moore" where the briefing text is only shown when the mission is started but not in the briefing screen. No idea why it's like this there, will provide fixed version too once I found out.