The bug is that unaware Ability is ignored when a pokemon that have his Attack or Special Attack boosted do a critical Hit.
Examples of how it works:
Official Pokemon
Unaware
+6 4 SpA Togekiss Air Slash vs. 252 HP / 4 SpD Unaware Clefable on a critical hit: 156-184 (39.5 - 46.7%) -- guaranteed 3HKO after Leftovers recovery
Non Unaware
+6 4 SpA Togekiss Air Slash vs. 252 HP / 4 SpD Clefable on a critical hit: 616-726 (156.3 - 184.2%) -- guaranteed OHKO
You can check by yourself in Showdown Calculator
Pokemon Revolution Online
Unaware
+6 4 SpA Togekiss Air Slash vs. 252 HP / 4 SpD Unaware Clefable on a critical hit: 616-726 (156.3 - 184.2%) -- guaranteed OHKO
Non Unaware
+6 4 SpA Togekiss Air Slash vs. 252 HP / 4 SpD Clefable on a critical hit: 616-726 (156.3 - 184.2%) -- guaranteed OHKO
So instead of deal +0 (+50% damage from critical hit), it is dealing +6 (+50% damage from critical hit)
Info
Unaware
If a Pokémon with this Ability uses a damaging move or is targeted by a damaging move, the other Pokémon's stat stages are ignored during damage and accuracy calculation.
Critical Hit
From Generation VI onwards, a critical hit deals 1.5 times a move's normal damage.
From Generation III onwards, when a move scores a critical hit, the attacker's negative stat stages, the defender's positive stat stages, and the defensive boosts from Light Screen, Reflect, and Aurora Veil are always ignored. However, the halved Attack from burn is no longer ignored.
Source: Bulbapedia