Launchpad currently recommends translating gcc-6 in Ubuntu Bionic.

Template "cpplib" in Ubuntu Bionic package "gcc-6"

Language Status Untranslated Need review Changed Last Edited By
Cherokee 100.00  100.0% untranslated 216 216 0 0
Dakota 100.00  100.0% untranslated 216 216 0 0
Hawaiian 100.00  100.0% untranslated 216 216 0 0
Inuktitut 100.00  100.0% untranslated 216 216 0 0
Lakota 100.00  100.0% untranslated 216 216 0 0
Ojibwe 100.00  100.0% untranslated 216 216 0 0
Spanish 000.00  100.0% translated 0 0 0 2018-01-24 04:18:48 UTC 2018-01-24 Cristian Othón Martíne...
Tlingit 100.00  100.0% untranslated 216 216 0 0
Yiddish 100.00  100.0% untranslated 216 216 0 0
[ Change your preferred languages... View template & all languages... ]

Template "gcc" in Ubuntu Bionic package "gcc-6"

Language Status Untranslated Need review Changed Last Edited By
Cherokee 100.00  100.0% untranslated 11993 11993 0 0
Dakota 100.00  100.0% untranslated 11993 11993 0 0
Hawaiian 100.00  100.0% untranslated 11993 11993 0 0
Inuktitut 100.00  100.0% untranslated 11993 11993 0 0
Lakota 100.00  100.0% untranslated 11993 11993 0 0
Ojibwe 100.00  100.0% untranslated 11993 11993 0 0
Spanish 021.28  78.720920537% translated  21.279079463% untranslated 2552 2552 0 2 2 2018-02-17 10:03:39 UTC 2018-02-17 Paco Molinero
Tlingit 100.00  100.0% untranslated 11993 11993 0 0
Yiddish 100.00  100.0% untranslated 11993 11993 0 0
[ Change your preferred languages... View template & all languages... ]

Template "libstdc++" in Ubuntu Bionic package "gcc-6"

Language Status Untranslated Need review Changed Last Edited By
Cherokee 100.00  100.0% untranslated 10 10 0 0
Dakota 100.00  100.0% untranslated 10 10 0 0
Hawaiian 100.00  100.0% untranslated 10 10 0 0
Inuktitut 100.00  100.0% untranslated 10 10 0 0
Lakota 100.00  100.0% untranslated 10 10 0 0
Ojibwe 100.00  100.0% untranslated 10 10 0 0
Spanish 000.00  100.0% translated 0 0 0 2017-07-18 17:35:00 UTC 2017-07-18
Tlingit 100.00  100.0% untranslated 10 10 0 0
Yiddish 100.00  100.0% untranslated 10 10 0 0
[ Change your preferred languages... View template & all languages... ]
Key to this table: “Unchanged” means Translated
and “untranslated” means just that, Untranslated

Other versions of gcc-6 in Ubuntu