Wow, thank you, I'm glad you liked it so much. Let's start from the beginning and see what I can answer:
Everyone is always confused about that character lol. I actually prefer not to say it so I can let people think about it, but I can say you are not totally mistaken with your assumption and are actually pretty close! I personally prefer if you think more about it instead of giving you the answer directly, but If you still wanna know for sure what happened I can tell you that someone in the Steam forums of the game managed to solve it, so you can look there to find the answer. Since someone "already solved it" I took the freedom of creating a personal blog too where I give some answers about One Thousand Lies and some other things: http://keinart.weebly.com/
The blog is bilingüal so you can filter to only english entries. Still I personally prefer if people don't try to get the answer from me at least until they haven't think about it first. In the other hand I prefer to give an "official answer" because I hate those pretentious authors that never give any answers, I always get the feeling that they never actually had any idea of what they were doing and are just letting the fans to fill the holes in their own story with whatever they can come up. One Thousand Lies contains some certains points that are open in purpose, but mostly everything has an answer.
About greek, yes I used a lot of greek! The story after all is a new modern interpretation of the Pygmalion myth, so there's a huge greek influence. Ciarán's surname is also greek, ενδυειν, that at the same time is a variation of another myth, the myth of Endymion. For Claire you are not mistaken. I thought that was a surname, I didn't know it was a name nowadays.
For Luce however I made a bit of a play there so even thought it can be read in Greek, the main meaning for her surname is not from Greek but from Latin (but we all know how Latin took a lot from Greek anyways), so her surname meaning is actually "Golden". Claire surname is supposed to mean "Silver" so take your own conclusions considering the story (this is also something that I answer in the blog, so take a look if you want).
Anyways thank you very much for reading and for your comment, I appreciate it a lot.