My impression from the original post was that she batted and then returned to the dugout waiting for the team to go on defense. But the question arose in the bottom of the inning, so her team was at bat, which is why I'm confused
abou the sequence.
A substitute is in the game once they are in position (offense or defense) and a pitch is thrown, play made, inning ended, etc. If no one was reported as a substitute for the unreported player, then I believe the unreported player is still in the game.