[Paul Puaux]

Hi Fed Fef,

just in case you’re still having this issue,
I’ve been searching around workflows between Sketchup and C4D.

As Darby mentioned it, make first sure that Phong tags are applied when importing from Sketchup.
The other trick is that surfaces are not buil the same way in sketchup and C4D, so select all your object’s points at the point-edit mode level (French version, so I’m not really sure about its english name, left-bar icon), and on the right-click menu, choose optimise, it should merge close points at the value you select, in this case 0.00, so that overlapping points merge. Previously to this operation, all faces are locked apart from the others, so phong smoothing operations arenot physically applicable. After this, your object is one, and faces do edge properly.
Hope it may help,
Regards
Paul