B772. Thanks for the correction.
I took my quote from the Garuda accident report which stated nothing about drowning after jumping from the aircraft:
1.13 Medical and Pathological Information
The fatally injured cabin crew was lacerated on her face, left part of the necks (i.e. fracture of the neck), fracture of the both upper arms, right femur, left lower leg, and all toes were missing.
The cabin crew death is presumably due to impact with the bottom of the river of the aircraft against the river.