I am not familiar with propagating the particular hibiscus moscheutos you have. I have successfully grown other swamp mallows, rose of sharons, and tropicals from seed. You are correct that many 'hybrid' cultivars are sterile, but these are namely tropicals. One item of note is that even though the plant does have good seed stock, the plant itself may be "sub par". What this means is although the plant has beautiful flowers, the roots, stem work, etc, may be flawed. Many times, quality growers will attempt to breed in good habits, or even graft in better stock. This also mainly applied to tropicals. The last thing to be aware of is possible patent issues. Many plants have legal paperwork that technically prohibits propagation.
I know this is probably more information than you needed, but it may clarify some of the data you researched. As far as your question about growing, trial and error works best for me. Read about seed 'nicking' and see if you get anything to grow. Hope this helps,
Ed

Thanks Ed. I assumed when people spoke of sterile,I thought no seeds were produced, interesting. This plant didn't come with "paperwork" does that mean I'm in the clear, haha? I'm finding there is a lot of trial and error in growing my garden plants. Some are certainly harder to get cutting to grow than others and then seeds, not as straighforward as I ever imagined. It is great learning about these and other garden plants.I appreciate yours and others posting on here, there alot of helpful suggestions.

Darren in Florida