Some how I missed the first post. While I have no experience with this one, I have grown Hibiscus from seed. Sorry my memory is foggy and cannot find my notes. Fairly sure I cold stratified for 30 days. Not sure about the scarifying.
If they have a hard seed coat, scarifying is worth a try. I almost always scarify when I run in to seeds that have a hard coating. I have tried chemical scarifying, but always come back to mechanical methods. Usually sand paper or nail clippers. For super hard think things, I have used a dremel tool carefully.
