I'd be lovely if we could specify, maybe in .spec files, which glibc locales we want.
This is a fantastic idea. Any chance of adding this catalyst?
My interest was in reducing the time spent generating locales, which I've now fixed in https://gitweb.gentoo.org/proj/catalyst.git/commit/?id=5fb710093c0d4643b981db7763f7f14d04e02d79 Marking as WONTFIX.