How many experts do you have in Bulgarian history, folklore and culture? Warning, PM only as this is a topic that's likely to trigger people from neighbouring nations. I wish I was joking
I don't think you lack experts in martial arts in this thread, so I'm not going to put my hat in that ring (and I don't feel qualified to talk about the regional arts or HEMA, despite studying them for years now, so I won't - most people don't know that they exist in the first place...not to mention the fact that both are really regional and what applies to one school might not apply to the next).
What else? Law major, international relations (my first major is in International Security), Bulgarian gamebooks, Bulgarian fantasy (and Russian-language fantasy, to a degree), Daoist philosophy...or my interpretetion of it, at least
I don't feel secure enough in my understanding of Chan-Buddhist philosophy and French language comics, so I'd skip that, too. But you can ask me if you don't mind potential inconsistencies or unintentional misinformation.