Wow i never heard about it, 30 missing characters and no publickey.
16^30 = 1329227995784915872903807060280344576
That is 120 bits complexity, and there is no publickey available.
Please Forget that puzzle is infeasible. We still can't solve Puzzle 64 bits (this is 16 missing characters)
For sure any gap is a complication and I think brute-forcing the key from puzzle requires a dedicated program, relying on existing solutions requires too many additional assumptions.
I agree with that, that kind of missing distribution require a specialized program.