I did one of these a few days ago and it was OK, although a few things confused me. Namely, some times I got a (rather short) timer after killing the victim, other times I didn't (I did several tries to get a perfect run). I got the impression that you only get a timer when you are detected, even if it's only once, but in one of my tries no timer was showing but I still got a message saying that I failed to exit before it ran out. Today I got the Trader's Cove and I have additional issues.
For starters, one of the optional goals implies killing one of the victims with poison. I thought this implied equipping a poison and using my weapon, although that doesn't seem to play well with the whole stealthy assassin and the Blade of Woe synergy... So I equipped the poison (the crown one) and used weapon attacks on the victim. Sure enough, I got a message stating that I did kill the victim using poison. But on the next attempt I killed him using the synergy (with poisons equipped but with no weapon attacks) and I still succeeded in that goal.
Also, in several of my tries the alert status was raised to 3/5 or even 5/5 as soon as I spawned in the zone, forcing me to abandon the quest immediately. In fact, I stopped trying to do the Sacrament because this happened 3 or 4 times in a row, so I was unable to start a fresh run.