It makes a lot of sense to rearrange the substrate slant once a week using a sand flattener.
Mounding the substrate and having it rise towards the back certainly has its optical advantages, however, there are disadvantages to this method, too, and you'll need to keep certain things in mind if you want to preserve the steep slant in the substrate over a longer time. Natural erosion and the activities of shrimp and other bottom-dwellers like e.g. armored catfish will cause the substrate to level out over time. Unplanted areas are especially strongly affected by this phenomenon. It makes a lot of sense to rearrange the substrate slant once a week using a sand flattener. When large sloping areas are planted with low-growing ground-covering plants, the roots of the plants will stabilise the substrate once the plants have grown in and start to fill the free spaces. Make sure you don't have any digging fish or inverts (or just a very low number of them) in the tank during the first weeks until the plants have taken root and grow densely enough to keep the substrate where it belongs. In addition, strips cut from PET foil or pond foil (marked by the red arrows in the photo below) can lend additional support to the substrate. Later on you can remove these strips when the plants have taken over, or you can just leave them in place and have the plants grow over them.