StephaneLamy: Since the problem is very symmetrical, the tree of solutions should also be symmetrical.
One missing variation (at least): K9L8K8K7J10H11 does not lead to any correct answer, but with J10 and K8 exchanged it does...
Note that this is the same problem as Pretty area #19, so maybe just cut and paste the complete tree of solution from there?
posetcay: I added your moves. I think most of the variations are covered already, the only one that was missing was the J10 after K8 shape you pointed out, so no need to copy/paste tree from the other problem in my opinion.
After K9 L8 , K8 is marked as incorrect, even when after K7 J10 H11, the position is the same as the correct variation