Hello there and welcome to BYC!
Molting birds generally don't lay. Especially Australorps. (Aussies only come in black) My Orps are notorious for taking months to get back to laying, additional light or not. Austalorps have more feathers than any other breed and its taxing on their bodies to come up with enough protein for both feathers and laying.
Your other birds may not be fully mature enough to lay also health issues can stave off laying, cold, bullying, not enough sustenance. Many reasons why birds don't lay. Egg eating is always a possibility. I personally don't like to add additional lighting as I like to give my birds a break from laying. Less laying means longer living birds that lay longer into older age.
All this being said, additional lighting needs to be 12-14 hours with at least 8 hours of solid darkness.
So glad you could join our community and Happy Holidays!
Its wonderful to have you! 
Thanks for joining! If you have questions, you will find your answers. 
There are loads of awesome helpful and active members that will help you if they can. 
Or I guess in the back yard! 
