Magnus is represented by an agency, they have written the book's English title on the website: "A half year, an entire life"
I translated it as "Half a year, a lifetime" before, I will start using what they have written:
WARNING: IF YOU ARE SENSITIVE TOWARD WAR RELATED CONTENT, I SUGGEST YOU TO NOT READ FURTHER
Let me make a guess on what they were filming these past couple of weeks:
I think they were (maybe still are) filming The Stupni Do Massacre scenes. Magnus has an entire blog post about the massacre and he also wrote about it in his book:
Here we have the real pictures taken from his blog:
Here we have a glimpse of what they were shooting (Thanks to anon who sent me Tomas' profile so I downloaded the stories and made these gifs):
The school they use for location is called "Osnovna Skola Ivo Selimovic" as you can see on the pic (I think they put a title on the school like they most probably changed the names of the characters).
Elma Fetić, the actress I shared here, did a performance about the massacre in 2018 (that is why she is a part of the project, I strongly believe. There will be heartbreaking scenes)
Moreover, there is a makeup designer named Pia Cornelius, follows none of the cast & crew, but I think she is working for the series, she was in Banska Stiavnica: