You can really only propagate corker cultivars by grafts and cuttings, not seeds. If you’re grafting your own, make the graft right at the ground level on JBP seedlings. Do it right at the root cuticle. For cultivars, Evergreen Gardenworks has the broadest selection.
‘Ondae’ was from Seattle-area Dave Dewire who died last year. I’m not sure who you’d get that cultivar from unless you can get some scion material. A few members here have it. I sold mine because it was a frustrating specimen, but it did grow nice cork. I’d suggest trying ‘Brocade’ or ‘Hayabusa’. ‘Taihei’ is a good grower too, so is ‘Kyokko Yatsabusa’, but both of those have long needles.
Best of luck, someone needs to carry that work forward for the next generation. Let me know if I can help.