So essentially, those eager cub decors that often clog your inventory or the tree from training, could be used to make a background!
For example, the craftiing recipe could be five of each eager cub decor type/color, to make Training Grounds. Training Grounds would be a craftable background that is like cub training, possibly with some cubs climbing a tree, and others racing in the background/playing! Like the flavor text you can get from training your cubs, it could be incorporated in this.

Any ideas are welcome, as this was just a random thought of mine.
I likely will make concept art once i figure out how to put pictures in these- for now you can just use your imagination of how it'd look like!

it could be during the championship event (since lions are training), or year-round!