These guards won't bother to search personally; they're not motivated by a sense of justice but by potential gains.
Until they find the person they're looking for, not a single cart will pass through. They detain all passing caravans here, and the merchants eager for trade naturally urge their guards or mercenaries to search the forest for someone on their behalf.
It's best if they can find them.
If they can't find them... it's not a big deal. That runaway "nun" was someone Lord Cabbin wanted, not what the Lord wanted.
After confirming the escapee either starved to death or was eaten by wolves in the forest, they would eventually release all detained caravans. However, in return, they would demand a fee from the merchants as compensation for their "investigation."
Those merchants, anxious and frightened, are usually happy to pay for peace of mind; those who trouble themselves are in the minority.
Of course, all this is based on the condition that the person cannot be found.
