I'm so sorry to hear about Nuka, I hope she feels better soon. You're doing absolutely everything you can for her.
I had a parrotlet who had something similar (although he wasn't really showing any neurological signs) but he had an enlarged liver - rescue so unsure what his past was but he was fed on canary seed for goodness knows how long. He would never touch pellets (and would never touch any form of pellet no matter how patiently or differently I presented it), when he got sick he was moved to a better seed mix. The avian vet advised for me to give him this tea (cooled) daily:
Dr Stuarts Liver Detox Tea | Holland & Barrett (hollandandbarrett.com) (as he was so small it was hard to dose with just milk thistle) - which helped a lot. He was on it daily pretty much forever and it gave me many more happy years with him. I managed to train him to enjoy the drink as well which helped a lot in terms of stress, I would give him something sweeter after, usually sweet potato or apple so once he learned there was good stuff after he happily took it.
Just thought I'd share my experience, hopefully reassure you a bit that being on milk thistle forever isn't too bad - it definitely was worth it.