Adding the feather supplement will help them grow back or foods with a little higher protein and B vitamins. I give mine organic grass fed(the milk they use) cheddar cheese and soft boiled eggs. My birds don't get as much unfiltered sunlight as I'd want for them so I also give them that vitamin D supplement. IRN are a little different than some parrots because they are in a food rich environment .In the wild IRNs eat seeds (germinated and sprouted mostly) grains, flower blossoms, vegetables, berries, nuts, leafy greens pollen and nectar. With some parrots of have to be careful about adding a too rich diet- but IRN have rich diets in the wild. I hope this helps.
Because your bird can not fly and once could I would add padding to his/her surroundings incase she tries to flu but instead lands hard on your floor and gets hurt. I used pillows and comforters.
Your IRN is beautiful and I hope you both have each other for many years.