If you reimport the Datasmith Scene Asset, you should see the newly added items like the gutters get added to your project and show up in the level in their right places.
Any meshes that you haven’t modified in the SketchUp scene will be skipped in the reimport.
about the reimport process:
https://docs.unrealengine.com/en-us/Studio/Unreal-Datasmith/Datasmith/Datasmith-About-Reimport-Workflow