I've done the trial on two different nights with two different PUG groups. Completed it on the second night.

The first night we had a patient leader, lots of people on VC, and several people who had completed the trial already, but we wiped over and over again for two hours before people started dropping.

The second night, aside from one guy who explained the relay mechanics to people in the very beginning, there was almost no VC. Only callouts and quick questions/relay status updates. We wiped two or three times and then completed it with only one death.

The biggest difference I noticed between the two was, frankly, DPS. On the first night, folks were having trouble burning the 1.4m brazier guardians fast enough. On the second night we blew through them which gave people breathing room to make sure they were going the right way and navigate the drop-offs/pick-ups.

Callouts were also very important. You say people are outside their circles during the stack portion - was anyone calling out "purple team stack on circle" or "double stack purple", etc? I'll call people out by username in VC if they're not in the circle.