$ rpm -qf "$(which fc-list)" fontconfig-2.6.0-alt1 If a I pass some language as the pattern to fc-list: $ fc-list :lang=udm; echo $? 0 $ and the result is empty, then two situations are indistinguishable: 1) there are no fonts available for the Udmurt orthography; 2) the Udmurt orthography is not known to fc-list. I suggest that $ fc-list :lang=qwerty $ should issue a warning that language "qwerty" is not known to it.
А смысл отслеживать именно тут все существующие, мёртвые и искусственные языки? Нет -- значит нет.