Enrick's hypothesis was indeed correct. Lucien never wanted to burn down the bridge; everything was discussed beforehand, part of a full plan. By making them seem like the Gold Section was trying to burn down the bridge, the third division of the enemy would be busy making sure the bridge isn't burned, wasting their mana reserves. And that would create another opportunity….something they would be using very well.
The professors and evaluators observed everything critically, and they all genuinely marveled at the ingenious methods that the Gold Section was using. Not everyone or every team can do such a thing or have the courage to attempt such. And they could also tell that the Golden Section was not in fact trying to burn down the bridge, and they could tell this by the property of the flame itself.