Here's what i see:
Overall, head sizes are inconsistent. This may be only be visible when the portraits are strung together.
Celes
Ear is too low.
Neck is too long, and bent strangely.
Torso is at roughly 3/4 view, head is in profile. Certainly possible, but a bit odd, particularly with the neck.
Hair is good.
Inside edge of the nose and mouth should come into the face 1 more pixel. Nostrils might be good too.
Soldier
Mostly good.
Head and shoulders are turned to our right, but the collar is centered directly at the viewer. It should angle.
Relm
A center line through the nose and mouth doesn't match the profile of the cheek and jaw. Or maybe it's the line of the cheek versus the near line of the jaw? Something in the perspective is just off a bit. Can't put my finger on it.
Pose is a bit of a neck-breaker, but not too bad. There's no real transition from the jaw to the neck, maybe the neck is a bit small?
Strago
A bit noisy, but mostly good.
Neck is a lollipop stick.
Locke
Mostly good.
The nostrils need work.
The collar looks like it is off-center. One edge sits halfway under the jaw, one edge curves in front of the face. Ok if he is wearing the coat pulled to one side, or the collar is meant to be larger on one side than another, but this isn't clear from the image.
Terra
Overall very nice
Hair is very nice
Bridge of the nose is a bit high, but it's a minor crit
Edgar
Hair and costume are fine
Face is a bit basic
Could use a stronger jawline
So overall, necks and collars need work. Noses in profile need work. The rest is rather good.
Thanks for posting these.
Tourist