I'm sorry you and your cockatiel are going through this. Birds are so hormonally programmed to reproduce that it's hard to stop them when it starts, even as you see, when the female has no mate (no avian mate, anyways). I have been through unwanted egg laying and it almost makes me not want any female birds, but some of my most beloved birds have been girls, including Rocky, my BFF budgie that hand raised a couple years ago. Your Kiwi sound like a great bird.
I assume you are letting her sit on the eggs and not removing them. Removing them will just cause her to lay more eggs. She will lose interest in them if they don't hatch after a few weeks. Not saying she won't do it again, but females generally stop when their nest is full and don't lay any more while actively incubating. Make sure she has lots of food close to her nest because she doesn't have a mate to feed her and you don't want her to neglect eating.
In addition to good diet and a mineral block I would get a liquid calcium supplement and add it to her water. Calcivet is excellent. She uses calcium from diet and from her bones to make egg shells and she's in danger of depleting her long term calcium storage. That can cause osteoporosis (brittle bones), trouble laying eggs, and egg binding which is usually fatal without immediate treatment. During the laying process, the muscles contract strongly pushing the egg out. If her blood calcium levels drop too low during the process the muscles can't contract strongly and the egg gets stuck. If she becomes egg bound it's an emergency for an avian vet but if you can't get her to the vet quickly, put a few drops of straight Calcivet directly into her mouth without delay. That will raise her blood calcium quickly and perhaps save her life. Oiling her vent and/or putting her in a warm steamy bathroom can help but the oral liquid calcium is critical. A vet can try to express the egg out of her and it can be successful but don't try that yourself. If the egg breaks she will get a massive infection called egg peritonitis and die. Do you have access to an avian vet? If so, bring her in for a consultation and advice.
I hope she does okay. There really is only so much you can do when a female bird does this.
