If it's ranged beyond 1", the TN would be 4 rather than the target's Parry. If it's adjacent on the grid, then it would need to be compared against the target's Parry.
It'll need to allow for an adjustment to the Attack roll and the Target's Parry when prompting for resolution. This can account for modifiers that might not have been included in the roll dialog or for statuses such as Vulnerable.
Comparing the attack roll vs the targets parry and identifying if it's a miss/hit/or raise. Ideally include ganguo but if not no biggie.