As a guy who went through FMS level 1 and 2, i can say that people can fail the squat test even with heels raised. Even giving that much slack into their system isn’t enough because of more severe problems in the hips/legs/ankles or other problems elsewhere like in the t-spine and shoulders.  Also remember the FMS squat test also tests holding the pole overhead in proper position as well and not just the ability to get your ass to heels.