I thought the reference was to blimp type balloons, I know there are people trying to sell the idea but I don't know if they have anything operational. But you're probably right, this is probably about buoyancy devices.
Raising heavy things off the bottom with buoyancy floats is a very tricky business. One major problem is that while you may need a lot of lift to unstick it, once it starts rising, the air in the balloons or whatever expands. So just when you want things to go slow, the natural tendency is for things to speed up to the point of getting out of control.
But if they just wanted to raise the empennage 30 feet or so for divers to be able to get at the data recorder location, that might be doable on short notice. But even that would require experienced experts and equipment that probably doesn't exist in Indonesia.
(There is a very interesting story surrounding the recovery of the US submarine Squalus in 1939. The first time they tried to raise it, it went out of control on the way up and the bow was at least 30 feet in the air before it reversed direction and sank again, breaking all the cables and destroying most of the salvage equipment.)