They changed this event slightly during the Feb. '23 patch. If you CoH the group behind the golems, they will rush you when you trigger the event. Then you get caught in a very annoying punt/summons loop. And I was trying to get the Darkened Heart achievement and it seemed to be very hard using this method. A lot of trial and error ensued...
What worked for me to get the achievement was to set up in front of the golems. Upon triggering I would wait for the golems to move twice toward the VahShir. I didn't have the DPS for one movement, and 3 was too much, the golems sometimes would not reverse course and chase me! In order to buy time to get the achievements you absolutely want the golems to move all the way back to where the boss stands.
So once the golems have moved toward the VahShir twice, then I'd click my AA step button and move my group behind the golems. At that point I'd gather up my group and engage the first 2 akhevans. They have a short aggro range and my SK has a huge hate step, so I'd have to run quickly toward the adds to pick them up so that they didn't kill my healers. Something casts a root on the tank so I'd have to cure that periodically to ensure I could keep moving away from the golems.
I'd burn from the start. I would also ensure that I stayed close enough to the golems so that they would reverse their direction and move back toward the boss. As I killed the 4 adds, I'd keep moving back and then engage the boss on his spawn point, and let the golems get close and then I'd move the group into the golem aura so we all got punted to the VahShir end of the bridge. I'd stay down there and let the boss run to that side.
Now my group had a good period to wait for the curses to begin. The golems would need to traverse the entire length of the bridge before I had to kill the boss to clinch the achievements. Previously someone said that you would get it if you waited 30 seconds after getting the cure, but I never saw that happen for me, I had to kill the boss to get the achievement each and every time I tried this.
At the VahShir end of the bridge, I would slow DPS the boss until one or more characters got the dot and asked for the cure. I would switch to adds as they came and burn them down. However, after 2 characters got the cure, I would beat the boss down to "win" the event, but I wouldn't open the chest. I'd drop the mission, replace the characters with mercs or new characters and repeat the mission.
Sometimes I would turn off DPS on the characters that already had the achievement so they would drop down the hate list. Even my tank was able to get it eventually. There is an event message when the boss curses someone, but you can't tell who unless you see them /say help. I would switch to that character and scroll in the MQ status window and double check they got the confirmation message they'd been cured.
Basically, all the information to do this was presented earlier in this thread but it took me a long time to internalize, digest, and apply it. One thing that would be helpful would be for the Lua script author to add a "Success" message in /group chat so the driver can see who got the cure correctly. I didn't feel proficient enough in Lua to do it myself.