one thing i noticed on my last question is that question-edit-duplicate-preview doesnt obviously show german duplicates if you ask a english question. I think this is a bit suboptimal and should be improved. Also because of search results on google. On japanese language questions seem to be mainly written in english.
I think we should also attract native-germans not fluently speaking english, but maybe there is a option to give a german question title in META-information of html-code or as smaller written subtext below the english question title? Im no expert here! Just an idea...