I noticed this on a fresh new installation.
Publisher doesn’t behaves like it should according to the introduction paragraph of the “Phrase” section of the add-on “During installation Publisher will create two phrase groups. Default, and Languages. These two groups can not be deleted as Publisher expects them to be present. When a language is added it will also be added to the languages phrase group. The langauges phrase group is used by Publisher when listing site languages via the module tags so the language name itself can be translated to the end user.”
The Default group is created but not the Languages one.
And thereby doesn’t add a new language to the languages phrase group when a language is added.
I think the bug is there for a long time now because I already noticed it on a former version (on another install) but I didn’t had the time to create a ticket so I just created the Languages group myself at that time.