Note to the translator: If I were you, I would stay away as far as damn possible from what you did with the credits. I understand your willingness to a) show appreciation to the people that helped you and b) encourage others through exposition to help you. But in terms of legality, you are admitting that you have accepted money to do the chapter, which is illegal in terms of intellectual property (you are not allowed to make money on someone else's work without their explicit consent) and in terms of untaxed labor (unless you have declared yourself to be a freelancer translator and are paying the corresponding tax). Avoid yourself potential trouble, be smart.