The place to discuss Quail.
Mustard seed sounds good, maybe you could also sprout this for them and feed it when the sprouts are about 1-2 cm long - just an idea. I guess you'll just have to experiment to see what they do eat - any smallish seeds or grains are worth a try. Sorry we can't be more help, from so far away!
I've just done a search for cumin and coriander as additions to quail food. Both seem OK, at least in 1 or 2 % amounts of total feed. Good luck - it seems you are going to be our Bangladesh local quail expert
Thanks for the suggestion and also for the compliment