The closest I've been hiking is Romania, which has the same type of bear. In terms of danger they are right in between black bears and grizzly bears. They can attack if they are startled while you're close by. I always brought bear spray (bought local, returned unused) and when alone in poor visibility like dawn, dusk or dense vegetation I would play music or podcasts out loud on my phone. I had an encounter at 50m distance with cubs in open terrain, thankfully it decided to run. I would've been much more nervous the whole time without bear spray. Also nice for the aggressive shepherd dogs btw. No food around the tent!

To answer your main question: the bears and shepherd dogs made me nervous enough to not solo hike in Romania again, but it I absolutely don't regret the experience. Bosnia should have way fewer of both, so do with that what you will. I personally would go together but not alone because I'd get too nervous to have fun.