Engine rooms have tended to be a very common place for fires to break out. It was enough of a problem that the U.S. Navy has some very specific training for just that sort of contingency. The crew hated it, but it sure beat ending up as a crispy critter whenever the real thing happened.
Even with the aggressive training we had, mainspace fires were responsible for two ships...a submarine and a destroyer...being written off as beyond economical repair in the early 90's. Looks to me like this crew was well trained to deal with this sort of thing, but I expect the Calypso will be out of service for awhile.
I believe that with hot exhaust manifolds around for any spray to hit, two easy risks are:
-changing filters when by error there is still pressure in the canister. I have the impression that this was the old Prinsendam's undoing.
-cracking of the fuel tubing that connects at the diesel injector. There is some industry problem about this going around. Different styles of fittings are showing different tolerances for the heavy vibration on the top of the engine. One of our coastal ferries had this about a year ago. Even with the watch crew right on it, they had to evacuate and use the CO2 flooding. By then car tires were melting on the deck over. Captn Erik Wood wrote of a bulkhead line breaking just from an (unnecessary) crash stop while backing.