Eh, from where I stand I think he would have shown the others as well, had they asked.
But Koana is not interested in anything that comes from outside of Sharlayan, Zoraal Ja just wanted to muscle through the test, and Bakool Ja Ja was his usual cartoony mustache twirling evil guy that planned on just taking the keys from the start, not caring about winning that trial.
However, considering everyone knew the participants of the trial, making one that is so obviously made so Wuk Lamat would win it... leaves a bit of a bitter taste, thats for sure.