Uuuuggh.
I didn't realized we cared so much for internal organs.
Here, let me try.
The main problem with the piece, that is present in all subsequent homage pieces in this series but most prominent in Jean/Logan piece, is the woman's body.
There are two specific issues:
the point-of-view of the bosom and
the torso.
Both issues are related.
In JSC's original piece, one can reasonably assume that Felicia's body is in profile.
Though obfuscated with her hair, and the fur of her outfit, pay special attention to upper chest area
(ahem).
Due to the point of view, Felicia's back shoulder is/should be lower than her front shoulder and should be behind her and not visible to the viewer.
Now look at the new pieces.
The shoulders are on the same level, and the back shoulder is forward
(towards the kissing partner).
This changes the perspective of the bosom, which the artist did not properly compensate for.
This also changes the curvature of the back, which the artist also did not properly compensate for.
They just used the similar lines/pose from the JSC piece.
This gives the appearance of an improperly elongated torso
(not in proportion), and a really awkward pose.
There.
Edit: