Here is the official 5e rules for fall damage if your curious.
Falling
A fall from a great height is one of the most common hazards facing an adventurer. At the end of a fall, a creature takes 1d6 bludgeoning damage for every 10 feet it fell, to a maximum of 20d6. The creature lands prone, unless it avoids taking damage from the fall.
I haven't noticed anyone falling prone from falling. Likewise I haven't noticed anyone rolling to not taking damage. So im not sure exactly how they are working out the damage in bg3.
Currently in BG3, characters who take fall damage go through the animation of landing prone, but then just immediately get back up. I assume this is a bug/oversight and Larian will fix this, since they already have coded going prone after a fall.
I don't think falling characters are automatically allowed to "roll to not take damage." The line about avoiding taking damage likely is accounting for feather fall, reducing damage to 0 via feats, etc
