Landscape Editing is not easily done in runtime game
I look into the LandscapeComponent class code, I found it is difficult to develop Edit features of Landscape in runtime.
Since many functions was guarded with ‘WITH_EDITOR’ macro.
Landscape isn’t designed to be changed in realtime that’s why, a lot of it’s speed and performance benefits versus regular meshes comes from the fact that it’s static and very easy to LOD and organise in memory. Collision is also baked in too.
You should look into the Procedural Mesh Component if you want to manipulate meshes at runtime, but obviously they’re nowhere near as fast or performant as landscapes, or alternatively write your own landscape system for runtime based on the engine one. Smooth voxels are a popular choice!
So random generated landscape is not easily done.
It is a highly requested feature and has tickets assigned, but its still low priority for Epic.
Meantime you may find interesting forum threads about with pointers if you do a search:
Thank you for pointing out threads, franktech.