Thanks for responding, @Sooz. Thanks for the info.
I completely understand. I created a thread some months back and one of the devs said it should be easy to implement and should take a few days : Symmetry Tiled brush painting - #8 by tiar
However, she also stated they would need someone to be available to do it. I fully understand that she wasn’t making any promises. I am guessing it hasn’t been possible due to everyone being busy as from the link you have provided.