I snapped these pics of a mutation Cuban around 7 years ago. The breeder was working towards establishing them at the time. From memory they were being referred to as Australian yellow Cubans. I know a small number of breeders acquired birds from this Sydney based breeder and recall seeing them offered for sale at a couple of bird sales back in 2014. I have no idea of the current status of this mutation, but would be interested to find out if anyone in the finch community does know?