It's okay to want to work with shadows and trying to do less academical photos. However, I think it's very tricky to do properly, because when it's not controlled there's often something distracting from the subject of the photo. When shooting cosplay, the cosplayer/character is your subject. On photos 1, 2 and 5, eyes are attracted mostly by the environment, which makes the photo look awkward : what's the photo about ?
Photo 2. would have been a lot better if the patch of light had been just behind the cosplayer's head.
3. and 4. don't have this problem because the cosplayers fill the frame, but not being able to see the eyes is a problem. I'm not talking about having the eyes in full light, just having a hint of their position would suffice. Here's a photo I've done some time ago :
The eye is in shadow, but you can see it. And the fact that you can see the eye makes it a lot more menacing.
I personnally don't care about academical rules, but I never break them just to break them. If I do, it's either not on purpose, or there is a specific thing I want to convey, and my rule-braking brings the point across. But if my rule-breaking just makes the picture look wrong, then I'm doing something wrong and should try something else.
Sometimes too, I break a rule to try to convey something, and people just think it looks awkward. Doesn't mean their eyes are full of shit, just that I wasn't obvious enough.