Aww what a shame. The same happened to me, I was given five when we came here and didn't check closely when we picked them up as I felt that would have been rude as they were a gift. They did mention that this particular hen might be a cockerel but were wrong about that. She is eighteen months old now and although it was just one foot when she was young, the other is slightly curled too now, she is a big girl but manages OK. She scratches and perches fine, is very bossy and lays nearly every day. Unfortunately her eggs have soft patches, something that has developed quite early, and as she is big and clumsy she usually breaks them and eats them. Because of all this I believe she has some sort of imbalace in her calcium use. She laid all through winter too, shame.
One of our Shumens also had two twisted feet. She wasn't hatched like this, but started to lose her balance early and no amount of trying to splint them worked, she was just too tiny. We decided to see how she went, and apart from early balance problems she did OK, scratched and perched when the time came. We called her Darcy as she danced everywhere at full speed. She started laying good strong eggs and became my favourite. Unfortunately she suddenly went down hill and died a couple of weeks ago, very odd, she was a good weight and still laying. Miss her like crazy.
In hindsight maybe both should have been culled at hatch, but they had good lives and Chubba is still going strong. Both acted as they should and were always in the front for any treats. So though your girl might be too old to help straighten her feet, there is no reason she should not have a good, productive life for however long it is.