I went through this exact thing with my cockatiel. She grew out of it by her second molt.
Young cockatiels are notoriously clumsy and a tendency for a young bird to break flight feathers is not uncommon. Vivi had a tendency to get them caught in the bars of her cage and they would usually fall outside it, up against the wall and out of sight behind the object the cage was on top of, except when they dangled for a little while. I also saw her break one accidentally when preening. Flight feathers tend to need to be bent in order for a bird to preen them to the end and young cockatiels don't know how much bend is too much, they don't have the experience. They have long wings and tail in proportion to their body size when compared with many other parrots.
My Vivi broke every last one of her tail feathers, all at different points, and a couple of them dangled awkwardly for a while before falling off. When the last two were dangling I took some scissors and trimmed it evenly. Then I clipped her wings because, sadly, with only 1/3 of a tail the bird had no balance in the air and was a danger to herself.
After her first big molt she continued breaking tail-feathers and such I kept her clipped, only to discover that this time she only broke 4 out of ten. After her second big molt she only broke one between that and her next molt.
Do not worry too much about it. But if the breakage starts to get excessive, trim the matching feathers on the wings so that they are parallel, otherwise it could lead to some flight injuries if your little ones wings are giving uneven lift.
I hope that helps.
