These two threads from 2021 and 2022, and the links from them, may be of interest to anyone considering a visit:
https://www.railforums.co.uk/threads/bosnian-steam.222935/
https://www.railforums.co.uk/threads/travelling-to-bosnia-herzegovina.233269/
I haven't investigated the current situation, but if it hasn't changed in the past year or two, Kriegslok activity consists of shunting at two locations in the Tuzla area, one of which has very limited visibility from outside the site; on the positive side, if it's still possible to visit the works where the locomotives are maintained, that might also be of interest. Not far away at Banovici you might, depending on availability of diesels, be lucky enough to find some steam shunting, which could potentially include a classic Bosnian 83 class 0-8-2 tender engine on the narrow gauge or, as reported in one of the above threads, an American WW2 design (or at least the postwar Yugoslavian version) on the standard gauge (
https://en.wikipedia.org/wiki/JŽ_class_62).
An organized tour would enable you to see more steam activity, but at least some of it would be arranged specially for the visiting group. That's not a bad thing in itself, but to me at least, it isn't the same as seeing steam locomotives going about their normal business 'for real'.