One could argue a mech is more humanoid. I'm not sure what's robotic about your model as I'm not too well versed in GITS, but it clearly look more like an attack helicopter, rather than what most would consider a mech. In any case, the consensus here seems to be as long as the model is mecha/anime related, it's fine. We don't exactly have an abundance of content here to be super granular with what's allowed. I actually asked the question a few weeks ago:
https://www.lemmy.zip/lemmy.zip/post/39092875
In regards to your paint, what kind of paint was it? Did you use thinner? What kind? When you say bumpy, do you mean like an orange peel?