Thank you for posting in the community and for pointing out differences with the import process. Unfortunately at this time this is the current behavior as pointed out.
The SKP import has not been updated to reflect the Datasmith import but we considering making it identical in a future release. If you could make a suggestion on the road-map for identical import location that would help put priority on this issue/limitation. Here is the link to the road-map: https://portal.productboard.com/7pu88c9kpmqtzt8hwg6arujh/tabs/4-under-consideration
If you import a SKP and Datasmith file or use Direct Link (via datasmith) you can rotate the SKP 90 degrees or the Datasmith content for it to be at the right location.
When importing a Landscape geometry it centers the topography and thus it needs to be manually moved. I recommend moving the gizmo when to the corner (as you have it shown in your example) then you can change the location using the transform menu to place it correctly.
Thank you for this answer and these different solutions. I hope that the next updates will take into account these differences between direct import and import via Datasmith.
Even if a 90° rotation is obvious, it can confuse team members, especially beginners.
For terrain imports, it seems to me that matching the origins between TM and the source software is still the best choice.