I think the answer to this question should be extremely blatantly obvious to anyone who realizes that:
1. the value of a die rolled can only be determined by a roll that occurs forwards in time, and
2. the value of any single die from a dice roll is determined independently from every other single die in that dice roll, because a "dice roll" is actually multiple independent events.
The question is: If during the roll dice step of an attack, I mistakenly roll less dice than I'm supposed to, can I just roll the remaining dice as long as the roll dice step has not yet ended (no enchantments revealed, damage not yet applied)? Or do I have to reroll all of the dice I rolled already?
And just in case of bias, I'll phrase this same question in a slightly different way: If during the roll dice step of an attack, I mistakenly roll less than I'm supposed to, can I reroll all of the dice I have rolled already plus the remaining dice that I have not yet rolled? Or must I only roll the remaining dice without rerolling anything?
I think the answer to this is obvious: Incomplete dice rolls cannot be rerolled, since if people could reroll incomplete dice rolls without using Temple of the Dawnbreaker or Akiro's Favor, nothing would stop them from INTENTIONALLY leaving out a single die in one of their dice rolls and THEN pretending that they merely forgot that die so that they could be allowed to reroll all but one of them if they don't like their original results for all but one of their dice.
Unfortunately, there are apparently a LOT of players who disagree with me about this, including at least one playtester and two (IMO) pro-level players who I highly respect. Their attempt at a counterexample was to say that if someone rolls too many dice, then all the dice are rerolled. I explained to them the fundamental difference between adding dice that have not been rolled yet, and subtracting dice that have already been rolled: that adding dice to a dice roll doesn't change the original values on any one die, but taking away dice after those dice have already been rolled and then rerolling them does change values.
My argument was ignored. I'm kind of hoping that they'll use their great intelligence to cure themselves of what I HOPE is just temporary lack of common sense. We do agree on one thing, though. We're going to need an official ruling to settle this issue.