It was posted in the Japanese section of the forum, but it turns out the way we previously thought conspirator works is wrong. 20 subtle blow and 15 accuracy is just the bonus if there is only one person on the hate list. As more people and pets conspire against the target the amount of accuracy and subtle blow increases. They said with 6 people on the hate list the subtle blow is capped at 50, and accuracy is 25. And while adding more to the hate list won't take the subtle blow past cap, having 18 people on the hate list would give 49 accuracy. They also mentioned that the job points for conspirator applies to everyone in the party, and that the reason why the bonus doesn't show up in /checkparam is because it is calculated at the time of the hit.

It does make me wonder how conspirator would work in something like domain invasion where everyone in the zone can be on the hate list.

All in all the ability is much more interesting now, and a little more useful knowing how it works. Now I actually feel bad I can't have it up all the time :/