[0]: https://en.wikipedia.org/wiki/Libyan_financing_in_the_2007_F...
First, this is mostly about things that happened before his election.
The tribunal ruled he did not personally benefit, and he did not directly solicit money to finance his campaign either.
However, some of his closest allies (who would become his ministers later) did the latter. The tribunal could not find any direct proof he was involved but ruled there were enough "converging indications" that he knew and did nothing to stop it.
There is no formal proofs, but as you say, (the judges deliberated that) there is enough "converging indications" to support the idea that the short explanation is true.
Sarkozy and all of his billionaire media allies are already trying their hardest to undermine the credibility of the justice system at every turn with extremely dangerous rhetoric; I dread to imagine what this would have been like had they gone with ever-so-slightly-less-safe charges