Cole was fully human in Asunder, he had to eat and sleep, feels cold and hot, he has scent and taste, he sweat, breath, bleed and weep, he can even dream.
Asunder p.12:
"If he was dead, why did he still sleep? Why did he still hunger, and breathe, and sweat?"
Besides, if he was not fully human, then how could a spirit expert like Rhys traveled with him through half of Thedas and still believed that he was just a troubled young man? I have the same feeling that his physical form is too complicated for an illusion of spirit, thus could be an implication of something more. A quote from Dorian: “That's something. I don't know what, but it's something."
Btw, his cloth are real:
Dorian: Cole, are those real clothes, or-?
Cole: They're real. What else would they be?
Dorian: I thought maybe you'd conjured them, like your physical form.
Cole: Do you conjure yours? Is that why they look like that?
Dorian: Never mind, forget I said anything.
When Cole decided to be a human, he can be a fully human, even Solas admitted that he did not see this coming. Cole once said: “Not every spirit can do what I can do, but I can.” in the fade, so he must be a special case, something we’ve never seen before. I also wandered, since spirits are ancient beings, they must have seen many tragedies though out centuries, so why it must be Cole? And why now? Maybe this special circumstance was partially credit to the real Cole’s magical abilities, like the mage Cole was actually a Hedge mage or something?