This is a scan of a novel that summarises the Secret of the Lost Kingdom in French, the version with the bonus pages. It's very informative the book because it gives information that is not present in the movie. It's sort of a in-production info book and novel. Translation below for one of the pages.
"What are they called? Their names are Tharma, Lysliss and Belladone/Belladona.
Where are they born? Inside Obsidian/the Circle of Obsidian.
Their powers are... Numerous and extremely powerful!
Where do they live today? They are trapped in the grotto of Obsidian. They are condemned to stare at Oritel's sword terrorise them, so bright and so close. (This is written as if it was during the movie.)
What is their future? They must fight fate to survive because of the ancient prophecie that foretold that a princess would finally defeat them: Bloom of Domino! Their goal is make Bloom disappear!"
Does anyone find this enlightening? The fact that this is the only time that names are stated for the witches is very interesting. I'm willing to believe that these might be factual because the activities from the book were translated from Italian, from what the credits and copyrights imply.
Let's make it clear that this can be subject to change. I want to believe this but it can be changed for production purposes.
Marvaud, Sophie. Winx Club: Le Secret Du Royaume Perdu. Trans. Maria Grazzini. Paris: Hachette Livre, 2008. Print.