What "remitted for a fresh hearing" means
The conviction ceases to exist and the case returns to the first-instance court to be tried again from the beginning, before a different judge. It is not an acquittal, and families should not be told that it is. It is a reset — and in a case where the first hearing produced a conviction on a flawed assessment of the evidence, a reset is a substantial result.
Why the assessment of evidence is a ground and not a complaint
Article 88 of the Criminal Procedure Code requires each piece of evidence to be assessed for relevance, admissibility and reliability, and the whole body of it for sufficiency. A verdict that recites the prosecution evidence and does not explain why the defence evidence was rejected has not done that. Article 389.16 makes findings unsupported by the evidence examined in the hearing a ground for quashing — which is what distinguishes this from simply disagreeing with the outcome.