HAHAHAHA... Kurapika has figured everything.
The part about the consequence of failure to complete the ritual was something I had been curious about since the beginning... I am surprised that it actually doesn't cause the death of the Hui Guo Ro family, but Kurapika's explanation clarified it well.
The deaths caused during the ritual are already "payment" enough, and as nen contracts demand willingness (even if specifics don't need to be said), if the ritual fails, the only thing that should be lost is what was gained by the ritual... which is the political power that the family has.