Langpacks dnf plugin is available since Fedora 21. This plugin provides various commands like langavailable, langinfo, langlist, langinstall, langremove. This plugin is a approved Change for Fedora 22.
This plugin also have QA:Langpack Dnf Application test cases to test it in Fedora.
Currently this plugin is having an issue of unable to update/install langpacks when base package is updated/installed. This is being discussed in bug reported against dnf. The solution is proposed now in Fedora 24 Change proposal.
The other issue was also of unable to have dnf-langpacks installed by default in Workstation product. This is now resolved in comps workstation product group by adding dnf-langpacks as part of that group.