While upstream provides us with plenty of complete translations for gnome-color-manager, in Ubuntu, those translations cannot be found due to absent translation templates.
Odds are, .mo files for a scale of languages are present on my system, yet none of them contain localised strings:
gnome-color-manager: /usr/share/locale/ar/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/bg/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/ca/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/ca@valencia/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/cs/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/da/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/de/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/el/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/en_GB/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/eo/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/es/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/et/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/eu/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/fr/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/gl/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/he/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/hu/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/id/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/it/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/ja/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/ko/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/lt/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/lv/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/ml/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/nb/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/pa/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/pl/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/pt/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/pt_BR/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/ro/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/ru/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/sl/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/sr/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/sr@latin/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/sv/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/ta/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/th/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/ug/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/uk/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/vi/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/zh_CN/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/zh_HK/LC_MESSAGES/gnome-color-manager.mo
gnome-color-manager: /usr/share/locale/zh_TW/LC_MESSAGES/gnome-color-manager.mo
This shows there must have happened some sort of misconfiguration to this package.