There is a badge for Bosnia, so if we would add region support it would be enabled. Do you have any insight in how many regions the should have? And if they are divided in some lower level as well? We usually import data from Openstreetmap, and I can see that their admin level 4 has 3 regions. But from what I can see, there is no other level that has complete coverage of the country.
I also tried to read up on the fact about number of regions. Usually wikipedia mentions in it one way or another, but I could not find any facts here.
Meanwhile I will add the country to our polygon-todo-list.