Acquittal in La Llorona (2019)

[AuYeung]

In Jayro Bustamante's La Llorona former dictator Enrique Monteverde (Julio Diaz) is convicted of genocide in a Guatemalan court. But the verdict is overturned when corporations (whose interests Monteverde had served while in power) convince a higher court that the prosecution had failed to prove that a genocide took place. (The 82 victims giving testimony apparently wasn't enough.)

A couple of reviews have said that the acquittal was the result of a mistrial which I don't think is correct. I know this is Guatemalan law we're talking about but it can't be a mistrial if a higher court feels the prosecution failed to prove their case in the original trial, right? AFAIK that would just be the original verdict being overturned in an appeal.

Please let me know if I'm missing something here.