It seems obvious to me that the spells are working as "designed", though who knows whether its as "intended." The heal does proc but since CB already went through the absorb and killed you the heal does nothing. Heals that land right after death dont resurrect you. Just like how I can cast a Gheal crit for 16k on the tank and lose the mana for it but the tank still dies because he was actually dead right before the heal went off and latency still let me cast it. CB vs AD isn't latency related but its still a heal going off after death and having no effect.
Just because the devs may or may not have thought about this particular scenario doesn't mean its intended or not intended. If they dont want to change the mechanics to prevent this scenario then the wording of the tool tip obviously needs to be changed to something like "Attempts to absorb the damage of any blow that would normally kill you. If the absorb is successful your health is raised by up to 30% of you max health. 2 min CD"
Poor wording of tooltip does not necessarily imply what was or was not "intended." Technically speaking the spells are working exactly as mechanically designed. There is no "bug" in the code.