Did Judas know that high-priests and elders' goal was to have Jesus killed? Gospel of Matthew tells us that he committed suicide before Jesus was crucified:

Then Judas, which had betrayed him, when he saw that he was condemned, repented himself, and brought again the thirty pieces of silver to the chief priests and elders, Saying, I have sinned in that I have betrayed the innocent blood. And they said, What [is that] to us? see thou [to that]. And he cast down the pieces of silver in the temple, and departed, and went and hanged himself. (Matthew 27:3-5)

which means that Judas never learned of Jesus' death and resurrection. However, the fact that he committed suicide may suggest that he knew that what had happened to Jesus because of his betrayal would imminently bring Jesus to death.

On the other hand, he might've not know that the ultimate goal of high-preists and elders was to have Jesus killed. He might've even been fooled by them, for example, they could've told him that