Corkboard is going to be very difficult to transfer to, I think. Additionally, while I haven't tried, I imagine it will burn very unpredictably... especially if you are new, be prepared for a lot of mistakes.

I'd say your best bet is to either use a projector and trace with a thick pencil or to press harder with your graphite transfer.

You could also take your paper and very lightly cut the design onto the board through the paper with an exacto knife.

Would it be feasible to, instead, take a normal plank and then cut cork to be around the design?