I agree CM. This to me seems to be a good attempt to recreate medieval 'scholarly' texts and to me he seems to be discussing the origins of fire in general, in much the same vein as frogs appear spontaneously from mud.
Good! For me these things make me overthink - how do such creatures come about? Did they recently adapt to draw energy from magic? If not, what did they use before intelligent races evolved and developed magic?
Where they the creation of some asshole god, or a wizard who wanted bugs to seek out magic items?
And here we see an excellent motivator for elves to seek adventure out of their utopic homelands.
And, visitors could get a major introduction in elvish culture once they inevitably fall into the 'servitor' role, as the elves, happy for something unusual in their lives, make the outsiders run all manner of errand in the city. Their unfamiliarity would likely lead to still more infractions making it harder to get out. Maybe they eventually cause enough chaos and disruption that banishment becomes a better alternative and that's how they break the cycle.