I do try my best, always room for improvements. Plumheads eat flower blossoms, I am lucky enough to find them at the organic market. Pi also likes some veggies clipped up and others he will eat from a bowl..so I need to mix it up.
in terms of cooked vs raw I feel any claim in a bit nebulous. Birds do not cook. Cooking will definitely ease digestion and start breaking foods down into more easily absorbed compounds. -Though in captivity there is an over abundance of easy calories that can also cause harm. I can understand that parrots wouldn't naturally have a lot of access to a root vegetable like a sweet potato, so cooking is probably ideal. Though when plumhead parrots are raiding agricultural lands in India, I don't think they worry about steaming their greens. There are different requirements per species, I do not believe I have a strong view that cooked or raw are better. From my understanding, African greys are known to have issue with calcium so perhaps it is critical for them to enjoy steamed greens.
Again I do the best I can by my birds I am not dogmatic one way or the other, all I want is a healthy happy little flock. Currently they get cooked grains: quinoa, black rice, freekeh. Most other things are raw. Is it possible that they aren't absorbing 100% of available protein because they nibble a few chews of sweet potato, it could be. However they are offered a wide range of options. They don't have sweet potato daily. It may be more critical if sweet potatoes made up the bulk of their diet. If I have any strong view it is that the little fluff balls need variety. They need to be excited to look in their dish in the morning, they need choices and seasonal selections. I offer mostly veggies, some fruit and then grains and some nut. They also have a commercially available vitamin powder that I add to the cooked grains (once cooled) to help with vitamin D and to fill the holes if they don't want to eat everything. Daily fruit is not a good idea for all species, however plummies are a fruit and blossom eating species.
I may have rambled a bit
This resource maybe be helpful for you and your lovely IRN.
DIETARY ADVICE FOR ASIATIC PARROTS (INDIAN RINGNECKS, ALEXANDRINES ETC.) » Currumbin Valley Birds & Exotic Vetrenarian - Gold Coast
There may be natural branches in your home country that can suit. Please be very careful about where they are sourced from-Never from an area that uses pesticides.
I would really enjoy reading over the resources you have. Most of the articles I have read on, oxalic acid, are related to human digestion. I am always looking for more info and would appreciate any sources you can toss this way