How are you calculating the accuracy bonus? The kneeling bonus isn't a flat added percentage to the displayed accuracy on the cursor, it's a multiplier. The 75% bonus (and that is the correct number from the ruleset) means that when kneeling the displayed accuracy should be multiplied by 1.75. If you get a bonus of +20% on that displayed number, that means your base autofire accuracy is around 26%, right? You're getting almost double accuracy from kneeling.
If that's not the case, then there could be a bug.