Made in Abyss Season 2 Episode 07 reveals how the Ganja fared after the reached the 6th layer. It doesn’t go well. One of the Interference Units eaten by an unknown creature. These units learn the human language quickly. They try to return to the 5th layer but human can’t maintain their forms after returning. Trapped, the Ganja resign themselves to their new home. The first issue is a lack of water. The are five possible location to get water. The first two are “swarming with dangerous beasts,” one has contaminated with “mining residue,” the other is too hot, leaving only one location habitable.
Irumyuui takes center stage as she can read unknow glyphs and later merges with a “Cradle of Desire.” The source of water the Ganja assumed was safe turns out to have been contaminated. The Ganja get sick developing diarrhea and causes their toes to melt and harden. It’s all gross really but that’s what makes this series so interesting and depressing. The Interference Units inform the Ganja that its an Artifact and is best used by simpleminded “juvenile’s” like Irumyuui. Since she’s sick, Vueko gives her the Artifact with Wazukyan’s permission.
Irumyuui merges with the Cradle of Desire
The following day the Artifact merges with Irumyuui, healing her and removing any pain. The Cradle of Desire grants Irumyuui her wish which isn’t made clear, but Vueko believes she wished for children because she creepily has several of them. Each one dies due to having no internal organs. Irumyuui has understandable emotional breakdown after each death. While she no longer experienced physical pain she does still feel emotional pain. Eventually, Vueko gets sick and is bedridden. Wazukyan feeds her a broth from a unknown source. When she awakens Vueko is completely healed. Something makes Vueko question what she ate, but before getting an answer Wazukyan says that everyone’s been healed and “that kid,” meaning Irumyuui “saved everyone.”
I think the Ganja either ate Irumyuui dead children or she produced food some other way. Since this is Made in Abyss eating dead creatures birth from a child seems most likely. Considering how much Irumyuui loved her child or at least thought she loved them it’s unlikely she was aware or happy about the Ganja eating them. This could be the reason she’s no longer in the village.