Lucas0231, planets of 55 Cancri A star system have all assigned names by IAU, 55 Cancri e being named "Janssen".
You may find it in ExoPlanets-custom.sc file, placed into the Catalogs0980.pak file.
The problem is the constellation reference, that you correctly reported as "Cnc" for the planet, but it should be used for the ParentBody as well:
Remove "Janssen" {ParentBody "55 Cnc A"}
Or
Remove "55 Cnc e" {ParentBody "55 Cnc A"}
should both work.
How do you make models for objects?
In order to make objects like asteroids or ships you need .OBJ and .MTL files of 3d shapes that SpaceEngine can convert in its own format, as described in
http://spaceengine.org/manual/making-ad ... ng-a-ship/ .
Several programs can be used to create those shapes, like Blender, 3DS Max, Maya only to name a few. I would add SketchUp, but I don't know if it has OBJ format support.