Complex is used to refer to the level of components in a system. If a problem is complex, it means that it has many components. Complexity does not evoke difficulty.
On the other hand, complicated refers to a high level of difficulty. If a problem is complicated, there might be or might not be many parts but it will certainly take a lot of hard work to solve.
Scenery is a term with generally broader in meaning than landscape (which may encompass landscape). It often refers to indoor settings.
Merriam-Websters defines scenery as:
1: the painted scenes or hangings and accessories used on a theater stage
2: a picturesque view or landscape
3: one's usual surroundings [e.g.] needed a change of scenery
Landscape is generally much more focused on natural geography (although it may be humanly enhanced or supplemente):
1 a: a picture representing a view of natural inland scenery
b: the art of depicting such scenery
2 a: the landforms of a region in the aggregate
b: a portion of territory that can be viewed at one time from one place
c: a particular area of activity : scene [e.g.] the political landscape
Except for the third aspect of the second definition, which is somewhat metaphorical, the depiction reflects a natural place.
Best Answer
As this chart shows, both terms have become far more common over recent decades...
My feeling is that encoded is associated with technical contexts where the method of encryption is more important than the encrypted information itself. Thus, from Google Books...
In more metaphorical contexts ("She declined my offer of a drink at the bar, which I took as a coded message that she didn't fancy me"), I definitely wouldn't use encoded.