First of all, thank you for your feedback. Second, I do listen to feedback, but not all feedback needs to be listened to.
As for the Trial itself - really, no significant RNG is involved, and a lot of people successfully finish the first Trial. And, no, the Trial is balanced the way I want it to be. If you want to pass a trial you have to either focus on one of the stats specific to this Trial (yes, stats - multiple, you don't have to focus on just one), you have to look for spells that would make the Trial easier, or you need to be very attentive during the Trial to know how it works mechanically. You cannot just try and bruteforce it. And that's the experience I want the players to have.
If you want to win a non-mandatory encounter, you'll have to work for that win. And it IS a non-mandatory encounter.