Hi Deni, thanks for reaching out.
The most accurate way to fix this would be to create additional terrain layers using better height data. However, as you mentioned that can be somewhat complicated.
Alternatively, you can flatten the appearance of terrain using a material effect and a Cartographic Polygon. Here’s an example of what that approach may look like:
Essentially, you’ll need to create a new Material Layer Blend and a new Material Instance to apply to your tileset, then mark out the areas in your level that you’d like to flatten with Cartographic Polygons.
You can read a detailed writeup of this process and further discussion in this forum thread.
Let me know if you have any further questions!
-Alex