>..and Limoncello (lemon-infused liqueur from neighbouring Italy).

Eh, as you mention limoncello is a liqueur while all the others you mentioned are brandies. Italy has it's own variety of brandies though. Grappa probably being the major one.

Correct me if I'm wrong, but judging by the name Borovničevec should be made of Juniper berries, bot blueberries.

No, borovinčevec is made with blueberry (latin Vaccinium). blueberry in Croatian and Slovenian is borovnica.

I'm sure there's a Juniper variant too, like I said "any fruit or flavour at hand".

There's definitely a popular blueberry one, google suggests that "Borovničevec" is it. However, I'm not the expert on Slovenian naming, I suggest that you try it under whatever name it goes by.