IMHO there should be no mysterious transformation of quanta. While it's fine for devourers (they eat any quanta to output black quanta) to do something like this, the crow/raven simply steals (shiny things). Therefor he should return the quantum in whatever element it originally was. Though, I don't really know how usefull this card is then... :/
Also I'm not really comfortable to "tack on" some elementalish name to put the creature into some direction... That's lame. And as such, the crow/raven is more a creature of darkness (especially with the stealing shiny things trick). But I doubt darkness needs more steals... though maybe..
What if the creature would be darkness, stealing the opponents quanta aslong as it's not dark too (for it's not shiny) plus no quanta-element-transformation?