Hydrogen embrittlement is certainly a very important concern in all metallic rotorcraft components. Halogenated cutting fluids can cause this issue while machining metallic parts and there is nearly no way to test for this effect in a fatigue lab setting.
Some OEMs
learned this the hard way
All that said, the fracture pattern from hydrogen embrittlement is fairly telltale, and it does not appear to be the case on these gears.