communicate with your mentor and research group. It will not work for you to have another student translate for you for the duration of your time at UNT. You have been placed with another Chulalongkorn student, so you will not be the only intern in your group, but this student is not Mr. Warath Winittamkul.
I think the best thing for you to do is to participate in the interview and have your mentor/interviewer determine if your English skills will be sufficient to participate in this program. If at any point you would like to decline your participation in this program, please let me know so we may make arrangements.