Try this formatstring ...
$replace($left('Artist 1, Artist 2 - Title',$sub($strstr('Artist 1, Artist 2 - Title',' - '),1)),', ',' || ',)resp.
$replace($left(%_filename%,$sub($strstr(%_filename%,' - '),1)),', ',' || ',)If you suspect any dash ambiguity then find there something useful ...
/t/16483/1
/t/15410/1
DD.20180128.1250.CET