https://replay.pokemonshowdown.com/smogtours-gen8nu-503196
Maybe it's impossible to fix in the calculator then? What I am trying to say is that Silvally forms with the memory equipped are always taking itemless damage as it is impossible to knock them, but the calc defaults to normal, item equipped damage. This replay shows it taking 12%, but this is impossible for item equipped damage and the item cannot be removed from Silvally.
They're both my teams being used, so I know for a fact the 12% damage is only accurate if itemless damage is being done:
252 Atk Mold Breaker Sawk Knock Off (97.5 BP) vs. 0 HP / 0 Def Silvally-Dark: 53-63 (16 - 19%) -- possible 6HKO
252 Atk Mold Breaker Sawk Knock Off vs. 0 HP / 0 Def Silvally-Dark: 36-43 (10.8 - 12.9%) -- possible 8HKO