Domino's critical failure will not ignore anyone's ability unless that champion is specifically has "ability accuracy cannot be reduced" i.e., Mysterio and Archangel.
Yeah that definitely should not be happening.
It could be the order of operations.... If Domino's -15% AA is applied first, you will have 85% AA. If the synergy is then applied, and adds it's 15% to 85%, then you have 97.75% AAedit: Actually this works both ways, regardless of which is applied first - you always end up with 97.75%, as long as the second modifier is applied to the result of the first...
You get critical failure if one of your abilities fail to trigger. When you first held heavy, your concussion didn't apply on Domino hence why you got critical failure