Maybe the following search parameters would be useful for somebody.
My music library is organized in the following way (example for Queen):
P:\Audio\Q\Queen\...
Under "..." I mean a subtree of folders with arbitrary names and depth.
There are files in FLAC format with empty tags in my collection. Only Title column isn't empty for such files and contains filename without extension, like "01 - Party". Therefore with default settings no lyrics could be found for such files 'cause there's no Artist data and invalid Title data (maybe the last thing isn't important, I'm not really sure).
The following search parameters analyzes Artist and Title columns. If Artist is empty and Title meets above condition (contains " - " and only numbers before it) then they takes Artist data from the path to the file being played and Title data as "right" substring of filename after " - ".
Artist:
$if($or(%artist%,$or($greater(1,$put(`seppos,$strstr(%title%, - ))),$not($greater(1$put(`tracknr,$left($get(`seppos),%title%))0,1$get(`tracknr))))),%artist%,$substr($put(`partpath,$substr($put(`fullpath,$directory_path(%path%)),12,$len($get(`fullpath)))),,$sub($strchr($get(`partpath),\),1)))
Title:
$if($or(%artist%,$or($greater(1,$put(`seppos,$strstr(%title%, - ))),$not($greater(1$put(`tracknr,$left($get(`seppos),%title%))0,1$get(`tracknr))))),%title%,$substr(%title%,$add($get(`seppos),3),$len(%title%)))