I understand what you're saying and know the terrains are flat, but didn't realise you can't remove the terrain due to it not releasing memory.

Either moving terrains is the issue OR not releasing memory when removing terrains. As moving terrains has been like this since I remember and there's no plan on changing this, our problem is not being able to remove a terrain efficiently.

If moving terrains were possible, you'd only need to create n amount of terrain tiles and move them around which you could just make in MED or at least prior to runtime and not require using ent_createterrain.

(You will always have the problem of not being able to exceed the limitation of a VAR though).