Thank you for the instructions on how to make one's own style.

I only need to change the formatting in the bibliography list, the
formatting of the notes in the text is entirely up to the requirement.

A strange effect (full MWE in attachment):

\btxdoifelse {address} {
   {\btxspace \emdash \btxspace \btxflush{address} \btxcomma}
   }

   \btxdoifelse {year} {
      {\btxspace \btxflush{year} \btxperiod}
      }

gives "year 2000", but throw out the "address" part, and the year goes
straight without the 'year' part.

   \btxdoifelse {year} {
      {\btxspace \btxflush{year} \btxperiod}
      }

if you add publisher between the address and the year, then it says
"publisher Brill"

\btxdoifelse {publisher} {
{\btxspace \btxflush{publisher} \btxcomma}
}

Where does it pull it up from?