And it is not evidence of a false accusation.
Lets see if I can make it easy for you. Imagine the following:
A neighbor comes round (lets call him Billybob) knocks on the door, and uses some pretext to get you to invite him in. While there, for apparently no reason Billybob lands a massive right hook to your face breaking your cheekbone. You go down. He walks calmly out of the door and goes home.
Baffled, you report it to the police. They go to see him and he says he’s never been to your house let alone hit you. You know he did it, he knows he did it – but he flat out denies it. His attitude is all off though, and the police are pretty certain he is lying. Only there is no evidence, no video, no witnesses.
Nevertheless, the police think you are a credible witness, he clearly isn’t and so it goes to court. The jury also think he is shifty, unreliable, and probably lying. Unfortunately the Judge (rightly) instructs them they have to be sure before they can return a guilty verdict. They cannot be certain based on your word alone against his – so the verdict comes back not guilty.
Amazingly – after this, your broken cheekbone doesn’t miraculously heal – he still did it. Innocent in the eyes of the law, but guilty in fact. And you certainly didn’t make a false accusation.
The important thing to remember is this is happening all the time. It is normal in cases where the only evidence is the word of the victim. Innocent until proven guilty (IUPG) is built on the premise
Better to let 10 guilty men go free than send one innocent man to prison
So no, your example – or a thousand of them – is not proof, or even evidence, of a false accusation. And found “not guilty” is not equal to “proven innocent”