The current processus is splitted in : translating the fbx file to an internal format, then processing the data based on content structure, metadata and settings, then generate assets and actors.
The … settings are settings that UE needs when reading the FBX file, while the rest are general import settings. And while you can modify general settings and see results immediately by hitting preview, modifying the translation settings will require UE to reimport the FBX from scratch.
So for now, there is a clear UI separation between translation/parser settings and the general import settings.
But I understand that, as is, translation settings are practically hidden.