Because of an active refugee community, we have lots of Bosnian restaurants around here, and I've traveled (and judged wine) at the other end of the former Yugoslavia, Slovenia (with a little dip into Croatia).
Based on this experience, I'm afraid a vegan Bosnian feast is going to be tough. South Slav cuisine is basically about MEAT. Beef and lamb, and flatbread and maybe a salad.
Check out this website, which is indigenous and probably more trustworthy than the crowd-sourced wiki. Unfortunately, it reinforces what I said above, with more details:http://www.serbia.travel/about-serbia/t ... bian/food/
If your folks are okay with the idea of using plant-based meat analogues, this is a field where the technology is rapidly improving as the market expands with aging Boomers and curious hipsters. Beyond Meat and Gardein are particularly good brands of faux meat; Simple Truth (distributed by Kroger groceries in this region) and LightLife (a brand of agribusiness giant ConAgra) are more corporate, but they all make surprisingly good meat-free substitutes.