Summary says that all, fontconfig can't pick up the appropriate fonts for Kashmiri for Devanagari script due to the lacking of the orth file in it.

How to reproduce:
1. install Samyak Devanagari font.
2. fc-match serif:lang=ks-in@devanagari or :lang=ks@devanagari

Actual result:
DejaVuSans.ttf: "DejaVu Sans" "Book"

Expect result:
Samyak-Devanagari.ttf: "Samyak Devanagari" "Regular"

Additional Info:
Aside from no orth file provided in fc-lang/, FcGetDefaultLang() seems ignoring @scriptname in current locale. so if lang= isn't given and run with LANG=ks_IN.UTF-8@devanagari say, fontconfig will set the default lang as ks-in.