As others have mentioned, she never gets to a proper trophy position (Note: do not think of the trophy phase as a trophy pose
). At the pseudo-trophy phase of her motion, her elbow position is way too high -- it should be in line with her shoulder tilt (in line with the clavicle line). It should not be lower than the clavicle line either. The high elbow position, relative to the shoulder/clavicle line is actually stressful to the shoulder (and may cause her shoulder problems when she gets older).
She also does not pull her elbow back far enough for her faux trophy position. The results in a lack of a pectoral stretch on the serve preparation. This is a stretch that should be present during the trophy and racquet head drop phases. It is released a bit later during the upward swing to the ball. Note the elbow position in the images below...
It may be best for Emily to abandon her full motion for a while. Instead, have her start her motion with the arm and racquet preset in the trophy position (even tho' I indicated earlier that this would not be a pause for a full motion serve)
. Have her start her serve motion this was for a while. Some players will start from this position for several weeks or even months. Some players, even quite a few pros, have adopted this as their standard serve.
With this "trophy" serve, make sure that she performs a proper racquet head drop (the so-called "backscratch"). She can also work on a full motion serve motion at the same time that she is using her trophy serve. However, she should only do the full motion with shadow swings for a while (no actual ball toss). She should not use the full motion for actual serves until she has done numerous repetitions of the trophy serve. Here is a video of a young Agassi using a very abbreviated preparation -- employing something similar to a "trophy" serve: