While I agree there should be severe and swift punishment for sexual offences, there should be some punishment for false accusations.

What are you talking about? There are punishment for false accusations. But that of course has the very same legal requirements of proven beyong reasonable doubt as any other accusation.

And no, just because someone is not proven guilty doesn’t mean that the accusation is false. It literally just means that, the court couldn’t prove the accusation and so couldn’t punish the accused.