It is correct or better to write soft pen calligraphy on the smooth or rough surface of rice paper. ...

The smooth surface is the front, and the pen is smoother, which is commonly used by beginners. Because the front is worse and more astringent, it is easier to master pen and ink.

The rough surface is the back, so it can be controlled with a pen. It can be used when the pen is fast.

Words written on a smooth surface have a long waiting time and taste good. The words written on the rough surface have been waiting for a long time, and the brush tastes particularly good.

This is my practical experience. For reference only.