Arthur didn't understand contracts.
But Arthur could make others think he did.
This wasn't contradictory!
As long as Arthur didn't encounter a true expert, he could make everyone believe he understood—this wasn't deception, merely a rational utilization.
Just like Kuke, or rather, Kuke's father, who must have known about the Mystic Side, but definitely did not have a deep understanding or any control; otherwise, Kuke wouldn't just be a Third-Class Officer of the Dort District, and Old Kuke wouldn't be confined to a farm.
Deceiving a layman was simple.
Deceiving a semi-informed layman was even simpler.
Because with a pure layman, you still need to lay groundwork and lead them to understanding, but facing a semi-informed layman, you don't need to explain much; just set the right atmosphere, and they will find many appropriate reasons to believe you themselves.
Just like Kuke at this moment.