In the Facebook Rollei group there is a guy who has gotten the FX-N and has posted some images like this one:
It shows a much closer focusing capability.
It seems as has been discussed other places that the camera front is the same as the FT which is why it is a bit thicker and racks out a bit further for the closer focus.
Looking at the photos of the camera on line:
It looks to me like there is no internal bayonet on the lenses which would mean that the filters and Rolleinars would have to somehow connect with an external bayonet like the shade does. I have no idea how they deal with that, perhaps an adapter that connects via external bayonet.
You might ask them at DHW how that works.