Yes. They mentioned during one of their streams (I think it was the one at the Bethesda meetup) that you have to do hard mode to get the 'good' ending. I can't confirm +3 from personal experience but for +1 the one survived and had a short chat with Olorime after the fight.

Lyserus wrote: »

^This..just finished it normal +0, but I wonder if we went +3 is it possible to save the others..?

Yes. If you do +3, you not only save the others, but you save all their power, so they are all back to normal and not weakened. It's the best ending. And it also gives you the best dialogue options for Olorime, who is stationed in Shimmerene after doing CR. If you don't save everyone, the situation is dire. But if you do, the situation is very positive. So you definitely want to do +3. Zone PUGs are doing it more and more frequently. It'll get easier as time goes on and everyone learns the trial.

kind_hero wrote: »

I did it +3 on normal... The ending is quite satisfying... at least for me it was. I saw the velkynars die many times, and Olorime crying about it, that when we saved all three, I was quite happy, even though they are virtual NPCs

After the fight, all 3 join Olorime near the dead sload boss, and each has some dialog. Olorime is happy, everybody will recover to their strength. In Shimerine you get a positive dialog with her.

You're such a... kind hero.