Wrong. It wasn't Cohen's job to report campaign contributions to the FEC. Cohen didn't even have a position with the campaign. It was the candidate's job.
If it weren't for the evidence, I'd agree with you. Unfortunately, Cohen's payment to Stormy Daniels came eleven days before the election and it suppressed information that might have been damaging to the candidate. Juries are allowed to make reasonable inferences based on circumstance. It's a pretty reasonable inference that this action was taken for the purpose of helping Trump as a candidate, not as a person.
The manner in which it could have been done within the bounds of the law was for the candidate to report the gift. Even to report it late or after the election would have at least mitigated some of this. Trump could still refile documents with the FEC today showing the gift. He didn't. He didn't do it after the election, or when the story broke, or when the search warrants were executed.
Trump's only possible defense would have been to show evidence that he directed his campaign staff to report the gift as soon as he became aware of it. But Trump himself stated that he repaid the gift personally - so he knew about it, but chose not to report it. He's still choosing not to report it right now.
And, incidentally, Trump repaying the gift personally (rather than the campaign repaying it) is meaningless. In one case, Cohen made an unreported gift. In the other, Trump himself made the unreported gift.
If anything, it's actually worse for Trump personally that he repaid the gift than if he hadn't.