You VI as EII-Ne, but that doesn’t necessarily mean you are that type. However:

1. Your aesthetics preferences do seem consistent with my VI conclusions. IEI-Ni’s normally aren’t as “expressive” in their artistic preferences. You also do not exhibit any IEI-Fe tendencies.
2. Yes IEI-Ni’s are very good at being chameleons, but the cosplay stuff are more up the EII-Ne’s alley (a consequence of Ne emphasis). You will also find this interest to be common in IEE (you could extend this to be a Delta and Alpha tendency, but it is more predominant in Delta NF’s).
3. There is somthing that you are subconsciously doing and needs to be pointed out. You’re Ne is spilling out into your posts. Instead of thinking intensely on one idea/conclusion and going from there, you use the thread as your own brainstorming board. This results in many posts in a row.
4. Theoretically, if you are an INFP 4w5 in MBTI, if this typing was obtained with assessing Jungian functions, then you should be an EII in socionics as socionics is a Jungian based cognitive theory as well (though you don’t have to believe this point, as the previous points should suffice).

In other words, I think you are an EII-Ne (or just an EII if you don’t like the Subtype system). I would say Number 3 is my best point here.

Of course I have more reasons, but to make sure there is little room for confusion, I will leave you with this.