The new editor TinyMCE appears in English even the Moodle is set to de_du or de_kids. Yes,  when I set the Moodle to the language pack de then I get a German tool menu but not with the language packs de_du and de_kids. The German tool menu must also work with the child packages de_du, de_kids, de_ch, de_comm, de_wp. 

I am a maintainer for the German language packs. I hope you will fix this problem as soon as possible because the packages de_du and de_kids are used in Moodle for students in primary schools who do not speak English.