It’s ok to make an error. Coaches are looking more at movement to the ball and arm. After an error they’re looking at how he responds. At the plate he drove the ball. Coaches are looking at his swing mechanics and how he responds to failure. Mental toughness matters. College ball will be the first time the game is challenging for a lot of players.
Unless your son is a potential future top round draft pick out of high school the best he can do is draw their attention. But he may not know until they see him as a recruiting prospect. They a,so may contact his travel or high school coach in the near future to tell him to keep working hard.