Is it safe for a newly hatched african lovebirds to eat the mixture of bread, vagetables and boiled egg?

Not sure just how "newly hatched" they are but, if you mean just a few days hatched, then the answer is no. Baby birds that new will only be eating what the parent birds feed them. It will be partially digested food from their crop. Little ones can't handle food that either hasn't been partially digested for them or is proper forumula being hand fed to them by an experienced hand feeder. If they are old enough that they have left the nest and are starting to pick at the adult foods on their own, that is okay. But otherwise no and you should not be trying to get them to eat it, if by chance that is what you are doing. Does that help?