Why should it even be doable in the first place? The Yozis were broken to their prison, the Yozis were broken to be their prison. Escape may not be a thing that can be accomplished without them ceasing to be the Yozis.
Personal opinion: Reclamation was a lie the Ebon Dragon told to the others, it was a lie he told to himself. The great betrayal of the Reclamation was not at the end of it, but at the beginning.
I usually run it that the Dragon always intended to renege on his promises. He loved the Reclamation. He cannot love anything that is not doomed. He cannot enjoy a story but that it is a tragedy. But is fixing the Yozis possible? Could be. But here's the thing: she's trying to undo one of the greatest and most terrible works of 700 primordial-transcending Geniuses who are individually capable of feats which spit in the face of the notion of impossibility. Forget the Salinan Working. Forget the Order Conferribg Trade Pattern. The Demon City is at once the greatest, most enduring, most brilliant, and most horrible of all the Celestial Host's accomplishments. They did what not even the Games of Divinity (which in some interpretations are even capable of breaking the Unconquered Sun) could do: they broke the surrendered Primordials.
As a bonus: in so doing? They broke EVERYTHING. Without the Demon City? Without the horrific mutilation of Theion into Malfeas, She Who Lives in Her Name's fury and despair could never have overcome her then-love for each and every thing to lead her to annihilate the best, her favorite, 90% of Creation.
Including the parts that permitted lasting peace, universal contentment, and incorruptible rule.
EDIT: but then again, I usually run off the theory that She Who Lives in Her Name wasn't always the principle of Hierarchy.
Before the Cataclysm? She was the Principle of Harmony. The ever-resonating principle of all things working in perfect and joyous synchronicity by their own choice.
If none can remember her acting thus? It is because the potential for it ceased to have ever existed in the Three Spheres Cataclysm. Hierarchy is, after all, only the bitter, realpolitik substitute for harmonious accord which is used in a world where the former is neither easy nor sustainable.
If She whispers now, it is because she cannot bear the dissonance the missing spheres introduced into the song some vestigial part of her knows should be. If She always whispered it is because none can remember a song that could never have been.
