I've been doing some google research - you know how I get a bug for these things.
In french Curio means the same as in english - a curiosity, a curious object, a rarity. (Corbeau means raven in French - they have a raven on their label, I've read that they are a French company. It's also a surname). Personally, I don't think it does mean leather, but I'd be happy to be corrected on that. Cuero means leather in Spanish, but I can't find that Curio means leather in any language?
I've seen similar Corbeau labels, with and without Curio - I haven't seen a gold plaque that the OP described, though I've read of it in a description. Here's two examples.
It seems more likely, as the OP says, it's either a different time period when they labelled their bags Curio, or a different line.
They do seem to specialise in exotic skins - every bag I've seen has been an exotic: ostrich, elephant, goat, zebra, buffalo. I wonder if they used the word Curio in their brand as a reflection of that? - ie an unusual skin, a curiosity, a rarity.
The bags without Curio on the label were also exotic skins, so I don't think it's being used simply as an indicator of skin type.
The two bags I've seen without Curio were from the 80s, and all the ones I've seen with Curio were from the 60s, or possibly 70s. So perhaps they simply stopped using the word Curio at some point, between the 70s and 80s. I can't find any 80s bags with Curio, nor any 60s bags without it.
I'm just hypothesising. I haven't managed to find anything definite, and can't find any company information.
Ruth