The nuts do not require loc-tite or other thread locking compound. The plastic caps under the bus bars compress under the screw force of the nut, applying tension to the nut and acting like a lock washer.
The caps themselves may come loose from the battery cells under extreme vibration if not reinforced. This is why we recommend adding some type of reinforcement to the outside of the pack, such as heat shrink wrapping or sandwich plates, to keep the caps compressed onto the cells in extreme vibration situations. See more here: https://vruzend.com/adding-sandwich-plates-to-ensure-continuous-connections/