Lost in Translation

Hi,

I'm trying to make a simple animation of a humanoid falling backward on his rear end in Blender, to then import into Unity. After much frustration using constraints, I am first attempting to get it to work with only "Rotation" and "LocRot" keyframes on all bones:

As you can see, he falls by rotating 90 degrees around the world origin, which is also the objects' as well as armature's root position.

In contrast, in Unity he firstly starts in a weird position, secondly maintains his center at the middle of the object, not at the world origin, thus bending properly, while not adjusting any positions to fall to the ground, hovering into a seating position in the air a la Dhalsim:

I have set root motion node to "None", "Root Transform", "Armature", the root bone, and the "spine" bone to which the rest attach hierarchically. All but "None" produce further undesirable effects.

Also tried with and without "Import Constraints", which by this point is moot as I removed them in Blender anyway just to get a working baseline, re-weight-painted many times, plus tried with or without animation compression.

You may see a number of import warnings which appear as well.

Further ideas I shall appreciate.

Regards,

Blitzen