Actually, I cook for my birds, they get a cooked mixture of approximately 40% whole grains, 40% mixed vegetables and 20% white beans and lentils. They get this mixture for breakfast and for all day nibbling along with a fresh raw fruit, vegetable and leafy green and then they get a good quality seed mix for dinner and depending on the size of the bird I give one or two almonds except for the parrotlets and budgies which I chop their almond up so that they get about a half of an almond each. The seed mix and the almond are the only high protein foods that they get. Watch to see what your bird picks out of your seed mix first and second as these are his favorites and pick them out of the mix to use only for treats. You can also use almond slivers for treats and if they like millet then you can use sprig type millet for a treat. The sprig type millet works best wile they are new to taking treats from you as you can offer it to them through the bars of the cage and break a small portion of it to drop in their seed cup if they don't take it from you at first. I never take a treat back once it has been offered as I think that it is important for them to learn that when I offer them something that it is theirs and that I will not take it back. I think that this simple act helps in gaining their trust.
Breeder birds from a commercial breeder are treated much different than are companion birds and this difference does nothing to earn their trust and in fact teaches them that humans can't be trusted. This is why they are so scared of humans, everything that happens in their world in which humans are involved id done to them regardless of how much they protest it. This is the type of conditioning that you are up against and why it is so hard to earn their trust. You can turn this around but you must not get discouraged, you must be consistent in trying to win their trust and you have to be patient because you can't push them at all as this what created this level of distrust in the first place, You have to listen to the bird and allow the bird to progress at their own pace. To be honest with you if you don't have their trust you don't have anything as everything good that can happen depends on this trust. I understand exactly what you are going through as I have a retired breeder myself that I am working with to earn his trust and it is not easy. One of the benefits to this is that when you finally do win them over you will be that much better at caring for your birds and will understand them that much better. Talk to me through PMs, or here on the open forum and share your difficulties and successes when they occur no matter how small they appear to be and I will share mine with you if you want, I will try to help you to not get discouraged if I can. I watch my Rajah and can see how caring and how intelligent he is while he is interacting with his new mate Keeta as well as watching him playing with their toys and can see his mind at work solving problems and can only imagine what a great relationship we can have together when he finally decides to start trusting me.