I have a problem with CATIA V5 R18. there is no control of curve smooth in "Class A" surfacing nor "Freestyle". I have been working in CATIA V5 R14 and we have had complete control of it but there is no way to do any thing else than "conversion".
I do not have R18 so I can not help you, but it sounds strange that there is not anymore an important function like that!
I think you should ask your reseller, if that function was moved to a different package (that perhaps you will be forced to buy... I do not hope this is the case!).
Please, inform us about the solution you will finally find.