That I don't know. As a matter of fact, I don't know the first thing about how the lanterns work. They're no technology I'm familiar with, if they're even technology at all.

[Might be magic. Everything might be magic in this damn place.]

But I don't think they're switching lanterns, just cannibalizing them to fix their own. You're right, though, the relationship here is mutually beneficial. They certainly make up for their suspiciousness with a very wide variety of goods.