Galvanic isolation probably wouldn't have prevented this fire, it sounds like the cells just shorted together. They would have had to short over several cells,

Galvanic isolation probably wouldn't have prevented this fire, it sounds like the cells just shorted together. They would have had to short over several cells, since a non-trivial voltage is required to break down coolant, so having maintenance contactors to break the pack up into 20V or so segments may have prevented this fire. Using a mineral oil type coolant that is not electrically conductive (such as used in Tesla vehicles) would have also helped to prevent this fire. The batteries should be galvanically isolated from the casing so that if liquid causes a current flow from any point in the pack, then the maintenance contactors can be opened and the opposite side current path for the leak is interrupted. We can only assume that they are already (galvanically isolated) since anything else would be bizarre.