Even the ranges given in solve() contains the results and should give all numbers;
Answers differ by range and most of them don't contain whole results.
Is this specific to this f(x) function or should we expect with others?

Regards

... refreshed for didactic.

Solve Complex Difficult.sm (18 KiB) downloaded 29 time(s).

In short, the Smath solve bloc is exceptionally robust and productive.
Somewhat not so evident to manage as in this example.
Silently, it takes the complex region not otherwise visible.
Yes, visible from the blank region, that suggests deeper insight.
The solvable range is trial/error, pretty unique in this example.
On the other hand, it is the twin companion of root,
but root is not documented as absent of the menu SS 6179.
Has root been added in the menu of your more recent than SS 6179 ?
Will soon publish these two companions root/solve.