"Untiring public campaign for hostages' release": a display of the european mainstream left wing public's delusion that having a baloon festival would accomplish something, or that the captors would be 'tuned in' to their view of the world or even care.
How self-inflated does ones' self-image have to be to think that this could accomplish anything?
The facts are found (or not found) elsewhere: the government denies paying blood money fo rtheir release (which guarantees a repetition of this kidnapping kabuki), but since they are mum about the terms of release, we have to rely on their history of dealing with these things as a guide.
Then again, if all it took was money, why did it take 5 months to find out who they needed to deal with? And what does France now owe the Syrians or a network of the shady leftovers from the Ceausescu era?