While perhaps the healing challenge is a touch overtuned for SM, it is definitely not bugged. I just completed multiple pulls of this fight in eight-man hardmode and went through the healing challenge at least twelve times. I successfully completed the challenge eight or more times in a row. I was on my Operative healer and was working with a Sorcerer. I have also sucessfuly completed the healing challenge in SM.
We failed the hardmode challenge the first four times we saw it on the initial two pulls. My fellow healer was also on his own Operative at the time and decided to switch to his Sorcerer to see if it felt any different. We were both geared in fully augmented 72s, and I had a 78 off-hand. The first couple pulls also gave us a feel for just how dire the situation was and how much healing was being asked for.
Diversifying our healing types was a noticable change as we were able to compensate for the weaknesses in each other's classes. He was able to slap down an instant purple pool before the captive was even able to be targeted, while I had to wait and extra couple seconds to be able to target the captive. I was able to bail him out at the end with surgical probe spams.
Specific Operative healing strategies were the following:
- Enter the challenge at the same time as all other people on your team (including tanks and DPS) with the healing buff from the boss' crystal, 100% energy, three stacks of tactical advantage and the following cooldowns available: clicky power relic (arkanian for me), stim boost, triage adrenal. My other relic was the Arkanian SA power proc relic.
- Pop power clicky relic once you're through the portal. It lasts for 30 seconds, which is essentially the entire length of the challenge. It will be off cooldown exactly when you are entering the challenge for the second time.
- The Sorcerer mitigated the inital plunge in the capitive's heath while I applied all my HoTs, starting with the ones that last the longest: kolto probe, kolto probe, recuperative nanotech, kolto infusion
- Time for a stim boost to speed up the big casts. I also have 8.9% alacrity on my Operative, so kolto injections that usually take 1.7 seconds are brought down to 1.5 - 1.6 seconds.
- Cast four kolto injections in a row (at least one should crit, I have around 27.5% crit)
- Use adrenaline probe to recover energy
- Cast two more kolto injections
- Recast kolto infusion
- Spam surgical probe as required until the challenge ends, and to help recover energy to prepare to heal the tanks upon exiting the challenge
I never had to actually use my triage adrenal, and my energy was above 60% when exiting the challenge so that by the time the tanks were back in my healing range I was at 80%+ energy. The Sorcerer and I had our rotations down so well for the challenge that we were keeping the captive around 20% health at the time it ended.
And for everyone that naysays alacrity and crit, this boss is just the prime example of where those stats shine.