I would agree that I would move it to a smaller container. I would also agree with moving it to a shaded but bright light area.
Your Huernia won't branch out a lot but it will drape over the side of the container. When it becomes too long, pieces can be broken off, allowed to callous and then rooted easily by laying on or tucking into the soil.
These are a carefree plant so don't obsess over it too much. Just enjoy it...
