
He was found guilty, actually, by his own admittance. It's the reason why judgeman gave higuruma the executioner's sword. That thing would only appear if judgeman finds the defendant guilty of a crime that deserves the death penalty. Yuji’s trial ended the moment he admitted to the crime, and the verdict was ‘guilty’.
Yuji being found 'guilty' of that crime is the reason why they are able to make sure that when sukuna gets into higuruma's domain, they would be able to put him on a trial that would result in a death penalty - by having a retrial of an already concluded case (that ended in a death penalty). This time with both Yuji and sukuna as the defendant. So it might be possible for sukuna to potentially pin all the blame on Yuji, depending on how good he is with words...
istg if the sins of sukuna will be charged on yuji in the trial