The decision on whether or not to use the reroll trinket is a risk vs. reward decision, where the risk is giving up the rolls you have now, and the reward is potentially getting better ones. Weighing the decision means considering how good the current roll is vs. how good it could be. When mentally evaluating the odds, whether or not the remaining active dice are 50/50 or not is a significant factor - e.g., a 6 on a D6 50/50 isn't as 'rare' (statistically unlikely) as it would be on a normal D6.
Doing something to visually distinguish 50/50 dice (shade them with a different color? invert them, black dice with white numbers?) might make scanning the active dice to make that decision easier for the player.