To "break the system", as it were? Whether that actually means fixing everything, or just undoing the Incubators' little energy farm on Earth, is another thing. As far as I'm concerned, at least, Walpy and Feathers are just here to give us a sense of urgency and an external threat, like Oriko at the start of the quest. Even if we beat them, I don't expect it to magically solve every problem of ours, just like beating Oriko didn't. I'd find it much more satisfying for this quest to end with us metaphorically and literally booting QB out of the solar system, personally.
With that said, I don't think dewitching and at least helping with the energy generation problem are impossible to achieve within our deadline. On the other hand, helping a traumatized person get better is something that takes months or years, and is definitely impossible in two weeks. The best we can really do, is set them on a path to recovery, and this would be the optimal outcome of our conversation with Homura here. We've done the same for Mami - she's not well by any measure, but she's slowly getting better (although she still needs a proper therapist, replacing her original issues with an overdependence on Sabrina is not healthy long-term either).
This is why I think our objective here should be to give Homura a different perspective on herself, something to counter her regular, unhealthy thought patterns. If we just reassure her without any substance behind it, it'll be the proverbial bandaid on an open wound; she'll feel better in the moment, but promptly backslide once left to her own devices.
