I have an idea- as some sources specialize in specific language/genre(s), maybe it would be good idea to search them first for these specific languages/genres? They have the biggest chances for a good fit.
Fe
- if a TXXX/ARTIST COUNTRY is Poland, tekstowo.pl and teksty.org would be searched first
- if Genre is *Metal* (* = wildcard), darklyrics and Encyclopaedia Metallum are searched first
Countries and genres would need to by assigned to datasources in code.