My bad with phrasing - what I really meant to say was that Spirit's sacrifices are more spiritual and don't attempt to manipulate the situation to their advantage (Darkness) nor attempt to desecrate the body (Renaimation, Death).
Obviously the effect is worth the cost or it wouldn't be played. That fits your definition of Darkness.
Death is not desecration it is utilizing decay or self inflicted decay to power its effects.
I did not claim the current cards in those series would fit the elements named. I claimed that the series would also fit the elements named if you consider the series as the mechanical series they are.
Example Death Spirit card
Poison both Players and gain N max hp.
I question the inclusion of Acid and Blood into the Mirror element category considering the Meta Elemental structure of ETG and the characteristics of Acid and Blood being far more specific than the current 12 elements. I think it would be fair to say that Mirror Elements do not exist.