Localize Activity Feed Into A Different Language

Hi there, 

we are deploying for a customer Dynamics 365 Customer Engagement v.9.0 and set the base langauge or default language to English, so we get quicker updates etc. 

So we translated all the display name and whats necessary for them to use the system in German. But we have a problem with the activity feed. We cant change the langauge of the activity feed into a different langauge. It mixes up the translated distplay names and the base langauge English.