How do I get correct scaling for sketchup in UE4?

Hello. I just read thought all this thread very interesting. Espcially the SKU > UE size
subject.
I am a 55+ beginner in UE5.03 Trying to get away from paying licenses SKU 19 towards Open Source.
I have had big problems, mentioned in other posts here, with Datasmith NOT working so I and trying to export “city indoor play ground” actors as FBX.
But many of my planes and faces still not show up.
As I am in an early stage of my concept project (to learn UE) I have.
TWO questions:
Would you recommend to export SKU19 actors without any SKU materials and then only add materials in UE?
Can it be possible that SKU faces that don’t have a double volume might affect the showing in UE as a FBX import
Meaning would I remove all the colours and materials for this stair case for example?


Or do I need to go back and make sure that all my faces have a thickness?
Thank you so much