The minecraft:transformation component is unable to rotate the 
minecraft:geometry.full_block geometry. Scaling and translation is intentionally disabled for this geometry, and a content log error will be produced if attempting to do so. But even if just rotating, no rotation seems to occur. It is presumed to be allowed to do this.
 
The attached world (Rotated Vanilla Full Block Geometry.mcworld) shows working and bugged examples. With any unit cube geometry, the obsidian face should be directed south. The working case is what should happen using the vanilla full block geometry. Its geometry is substituted with a matching custom unit cube geometry.
 
The working example is set above the blue concrete:

 
The bugged case is set above the red concrete:

 
 Both block definitions are also directly attached:
working.json
bugged.json