One possible theme could be the fear of the unknown. Since it's a horror story, the 'bhuter' (if it's a supernatural entity) represents something that people don't fully understand.
The 'bhuter golpo horror story' is a bit of a mystery to me. However, generally in horror stories, there are often themes like fear of the supernatural. If 'bhuter' represents some sort of supernatural being, the story could be about how people in the story interact with it, perhaps being haunted or chased by it. It could also include elements of mystery, where the characters are trying to figure out how to get rid of the 'bhuter' or solve the mystery behind it.
The Bhoomi Hindi movie does have a basis in true events. However, it also incorporates fictional aspects to make it more engaging and cinematic. But the core inspiration comes from real-life circumstances.
Yes, there are some Hindi movies based on true stories that may have been released on Thursday. But it depends on the specific movie you're looking for.