The case 1 should not happen as the preparation algorithm should ensure this. Do you have an example or is it possible to have a link? Or the process prints the landmarks after the creation as GeoJSON - could you attach this here?
Regarding 2: what do you mean with “landmark borders”? Do you mean routing from e.g. Germany to Turkey?
The default installation does a few things (splitting the area) so that requests inside are faster but cross-border requests will fall back to the slower non-landmark algorithm. To avoid this you specify your own GeoJSON border to split the area (or an empty GeoJSON to avoid splitting):
This might have a negative effect on the speed of the rest of the routing requests, so you might want to increase the used landmarks (likely you’ll need more RAM):