I found that with questions https://answers.unrealengine.com/ is a place that answers them super fast. And by fast I mean like an hour or less.
Also, I really like what you did with the Eren model. Looks GREAT!
And legally where you are now, you are fine. At this point the worst that can happen is if the people who own the rights to this happen to see this post, happen to get offended for god nows what reason, and then just asks you to take it down. It won’t happen so don’t worry =D Keep up the good work. Looking forward to seeing what you will do next with this guy! PERHAPS A TRANSFORMATION?! And of course he can’t fight alone!