Should I change Cynthia's Look?

You're quite a good drawer in my opinion, and you don't need to alter your character. However, always the stickler for canonical law (what the ipakita says trumps all tagahanga work), I suggest the following: if your character is an Irken, she should be wearing a backpack and also should be flat-chested. Canonically speaking, Irken creatures can not survive madami than ten minutos without wearing their backpack and, at least according to the depictions of Tak, Irkens do not have breasts. (Also, considering that Irkens are conceived through a cloning-like process, there would be no need for them.)

i agree that you should not change her look, but i do have to say one thing. tak was a very young irken(only 10 or 11 earth years) so based on that i would say that no one knows if irkens are flat chested or not.