Astarion, with gloves of thievery, (advantage, so 2 dice rolls) will still get critical failures trying to disarm a trap. Critical failures are a feature of the game.
His chance is 1/400, so yes, if you steal a lot, you WILL see it every once in a while.
And a Halfling with the same gloves (or the corresponding robe, or the corresponding spell) has a 1/160,000 chance for a critical failure.
Finally any Rogue 11+ will never roll a critical failure on a skill roll; their minimum result is always at least 10.
