Hi everyone! I'm also a semi finalist for Poland, and thought I'd share some insight I got from my program advisor: he said that part of the reason for interviews is to suss out language ability, and that since I'm a heritage speaker, it's likely that most, if not all, of the interview will be in Polish. But it also depends on the country-- apparently last year our research applicants to Russia and Mexico had their whole interviews in Russian or Spanish, but applicants to Columbia had most of theirs in English, for example. Anyway, it's something to potentially prepare for. (I, for one, am super nervous about this possibility because my speaking isn't very good at all, eek.)