"Pandemonium" seems like an odd state for judges to be in right before they appear to hear cases. But the egwugwu are not actually confused or disorderly. They are deliberately making their voices sound that way in order to scare the villagers into believing that they are the ancestral spirits of the clan.
The house was now a pandemonium of quavering voices: Am oyim de de de de! filled the air as the spirits of the ancestors, just emerged from the earth, greeted themselves in their esoteric language.
an elaborate and remarkable display on a lavish scale
First, there was the pandemonium of voices, accompanied by a metal gong and shrill flute. Then the egwugwu put on a spectacle with huge masks and smoke. This is all to terrify and convince the clan into believing with their ears and eyes that the egwugwu are ancestral spirits, so that whatever decisions they make would be too sacred to be challenged.
And when, as on that day, nine of the greatest masked spirits in the clan came out together it was a terrifying spectacle.
The staff agitating on its own after Evil Forest thrust it into the ground could mean: 1) The egwugwu have a powerful staff, so their words should be obeyed; 2) Mother Earth is moving the staff to show that the egwugwu's justice comes from her since she'd allowed them to reemerge; 3) Achebe is alluding to the biblical Moses and Aaron's staffs that produced many miracles, including turning into a snake when cast down.
Evil Forest then thrust the pointed end of his rattling staff into the earth. And it began to shake and rattle, like something agitating with a metallic life.
Another definition of "submission" is "an agreement to abide by the decision of an arbiter"--this also fits the example sentence because Uzowulu is about to present his case of his runaway wife to the egwugwu.
Uzowulu bent down and touched the earth with his right hand as a sign of submission.
Tortoise's volubility is connected to his cunning. While volubility is valued by the Ibos because it can bring people closer together, cunning is not because it destroys trust for individual gain. This is emphasized in the ending of the folk story, where Tortoise is justly punished for his deception and greed.
Tortoise was very happy and voluble as he flew among the birds, and he was soon chosen as the man to speak for the party because he was a great orator.
She remembered that night, long ago, when she had seen Ogbu-agali-odu, one of those evil essences loosed upon the world by the potent "medicines" which the tribe had made in the distant past against its enemies but had now forgotten how to control.