Each Croatian hunting agent (or foreign hunting agent), covers the same regions, and same outfitters.
Outfitters who operate various hunting areas in general do not advertise around, and they are basically local hunting clubs.
Bears bring income to pay concessions etc., while club members focus in most of cases to hunting boars, and roe deer.
The regions to hunt bear in Croatia most likely will be central highlands of Gorski Kotar or Lika.
Bears hunted in other regions are sporadic, usually those are bears that move away from bear country looking for new areas to settle.
If it is not Gorski Kotar or Lika - it is not prime area for bears.
The population of bears in bear country is dense (only few counties there), and increasing each year. I think the present population is about 1300 bears, and annual quotas are about 10%, cca 130 tags for entire country annually, but this quota is never reached, so population is increasing.
About the gun culture, and guns. I put this comment on my Croatian thread:
General premise is "your gun is your business, your problem, and is considered - zeroed in".
And in many cases outfitter will not expect you, or ask you to check the zero before hunt.
So, once you are in process to book the hunt, point this out to booking agent, so he can advise the outfitter, to prepare the range, so you will check the rifle before the hunt.
It is no problem to organize, but do not let them to be surprised for this request, on a first day when you meat the guide.
The guide will probably be a local hunting club member who knows the area well.
If you hunt with rental rifle, also be diligent, and ask to check zero. Not all rifles are zeroed, gun culture is low.
Hunt is usually on a bait, dark hours. Night vision or thermal clip on, is basically a grey zone. Legal for boars, but not bear.
Suppressors or silencers are not legal.
There are two seasons in spring and in fall. Spring season is better because of winter fur.
Minimum caliber requirement for bear: 3500 joules at 100 meters, minimum bullet weight is 11.50 grams. (minimum requirement - 2581 foot pounds at 110 yards, bullet weight 177 grain)
Bear will come at bait. But the hunter must be persistent. So, book minimum 7 days, even better 10 days. Then you will have a good chance for success, very high chance. Three days is short.