Launchpad currently recommends translating gtk+3.0 in Ubuntu Cosmic.

Template "gtk-3.0" in Ubuntu Cosmic package "gtk+3.0"

Language Status Untranslated Need review Changed Last Edited By
Cherokee 100.00  100.0% untranslated 1666 1666 0 0
Dakota 100.00  100.0% untranslated 1666 1666 0 0
Hawaiian 100.00  100.0% untranslated 1666 1666 0 0
Inuktitut 100.00  100.0% untranslated 1666 1666 0 0
Lakota 100.00  100.0% untranslated 1666 1666 0 0
Ojibwe 100.00  100.0% untranslated 1666 1666 0 0
Spanish 000.00  100.0% translated 0 0 20 20 2018-10-04 08:16:06 UTC 2018-10-04 Daniel Mustieles
Tlingit 100.00  100.0% untranslated 1666 1666 0 0
Yiddish 097.78  2.22088835534% translated  97.7791116447% untranslated 1629 1629 0 0 2018-10-04 08:15:54 UTC 2018-10-04 Raphael Finkel
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Template "gtk-3.0-properties" in Ubuntu Cosmic package "gtk+3.0"

Language Status Untranslated Need review Changed Last Edited By
Cherokee 100.00  100.0% untranslated 2243 2243 0 0
Dakota 100.00  100.0% untranslated 2243 2243 0 0
Hawaiian 100.00  100.0% untranslated 2243 2243 0 0
Inuktitut 100.00  100.0% untranslated 2243 2243 0 0
Lakota 100.00  100.0% untranslated 2243 2243 0 0
Ojibwe 100.00  100.0% untranslated 2243 2243 0 0
Spanish 000.00  100.0% translated 0 0 28 28 2018-10-04 07:48:40 UTC 2018-10-04 Daniel Mustieles
Tlingit 100.00  100.0% untranslated 2243 2243 0 0
Yiddish 070.80  29.2019616585% translated  70.7980383415% untranslated 1588 1588 0 0 2018-10-04 07:48:33 UTC 2018-10-04 Raphael Finkel
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Key to this table: “Unchanged” means Translated
and “untranslated” means just that, Untranslated

Other versions of gtk+3.0 in Ubuntu