I'm sure the recorders will be just fine. The AF447 recorders were OK after a crash which caused the aircraft to disintegrate and killed all on board, and after several years at a depth of 4000 m. So these recorders will be just fine after a ditching that all survived, and after a couple of years at 40m. I don't think the ATSB need lay awake at night worried the data on the recorders will be unrecoverable.
Sorry. I suspect my comment was a little too tongue in cheek to be seen as sarcasm.