I literally think it conveys no information at all. It's a metaphor, and a metaphor that the hearer won't understand unless he already knows the answer to his question. He could just as informatively have said "it's complicated".
A family member of mine works in the space academically, and they really have giant catalogues with pictures of fragments, and they experiment with different arrangements and what they would mean to their translation efforts. Unfortunately I don't have a link. :/
EDIT: a random CS paper that talks about automated solutions to the pure assembly part of this (without the text translation): https://arxiv.org/abs/1812.10553
“It’s like a puzzle” at least tells me there are a bunch of pieces to assemble, and gives me some insight and a basic mental model to start with.