The issue is, as best I can tell from your spreadsheet, is that the "Bonus Damage" in your formula is the incremental bonus damage from the augments, 52 and 57 for aim and power respectively. You need to use the full bonus damage and not just the incremental bonus damage to properly reflect the benefit of additional critical chance. The bonus damage for a full WH pyro build should be in the order of 850-1000, depending on the specific build, not the 52-57 value that you are using.