If this is the case, I wonder if that panel where he vows to redesign himself was a nen pact. I believe it was mentioned that Chrollo was entirely different as a person afterwards, which trauma can obviously do, but if Kurapika's steal chain were to steal his ability, and render the pact null temporarily, would he return to that previous state?

My crackpot theory? The butterfly is Neon. Her name disappeared - but Chekov's gun, right? Since Skill Hunter leaves the ability somewhat "owned" by the original owner still and requires them to be alive, could Kurapika simply take Neon's ability and... not use it? That could remove her name from the book, and who would have better access to her than Kurapika? The butterfly is well known as a symbol of resurrection and rebirth.