I am so sorry for your loss of Lorka and yes many birds get this disease and not much can be done for them, I know another bird would not take Lorka's place but you do seem to have a strong love for these awesome creatures, maybe one day when the hurt is less tender as it is right now you can think about bringing another one into your life and your heart.
Birds should be seen by an avian vet as soon as they show the slightest signs of sickness for birds are notorious for hiding illness until they can no longer do so, maybe if it was caught much sooner she might be there with you right now but I know those kinds of vets might be in short supply where you live.
I do give my grey peanuts in the shell but they are the roasted unsalted ones meant for human consumption, I throw away the ones that come in seed mixes for that very reason of the fungus you speak about.
Again I am so sorry for your loss but know that she was happy in the short life she shared with you and your family and remember those memories.