I think you're doing brilliantly! Just look at all the progress you've made already.
Perhaps you could concentrate on the door of the cage? I fixed a perch just outside the door of Dominic's cage so that he had a sort of 'goal' to see and aim for. You could sit patiently, holding a treat or toy or something Rose enjoys and simply wait for her to arrive in the doorway of her own accord.
Two fail-safe treats I've used with Dom are sunflower seeds and peanut butter. Now, we all know that both these are fattening and not good for our birds in the long term. HOWEVER, if you're trying to achieve something important, they make a truly spectacular reward. I think birds view them with the same kind of obsession with which I view chocolate...
Anyway, you might need to teach Rose to enjoy these treats by offering them to her often. You'd be surprised how daintily a Galah can beak a tiny smear of peanut butter off the tip of your finger. My Beaks will lick away until there's no trace of peanut butter left, but Dommie hasn't learned to do that quite yet. The thing is, they've all learned to love peanut butter and so I can use it to my advantage while training.
Other good treats are raw unsalted peanuts cut into small pieces; almonds, also cut up; a smear of honey on your fingertip; dry ramen noodles broken into very small, parrot-sized pieces; bits of crisp crust off a piece of toast; bits of dried fruits (eg. mango, pawpaw, banana etc). Obviously, the healthier treats are less popular than the unhealthy ones, but use your judgement.
Millet spray is very popular with some birds, not so much with others. It's VERY useful if you have a hand-shy bird because it puts some distance between yourself and your target. Other 'arm's length' treats could include a stick of celery; a small carrot; a parsnip or anything nice on the end of a skewer or chop-stick.
When you have one of these abused/neglected birds, you have to do exactly as you're doing and gain their trust. Eventually, you can teach them to enjoy treats and toys. That's not easy, obviously, but I think you have exactly the right attitude and that Rose will gain hugely from your efforts in the long run. Remember: it took years for her to lose all her confidence; it may take years for her to gain it back. I can honestly say that my Dominic is the most endearing of all my birds because his friendship has been the hardest-won.
PS. I inherited Dom as a 25-year-old who had been sadly neglected for the ten years since my father had died. It was no one's fault, just a very sad set of circumstances. Since then (three or four years now ), Dom has learned a great deal: how to fly; how to enjoy treats; how to play with toys; how to chew bits off my house and, most recently, how to negotiate obstacles as he flies around the house. Don't give up on your Rose - there is NOTHING as wonderful as a cuddly Galah!
