Hello Karl Golling,
Thank you for writing.
You can achieve this with a method that recursively iterates through the nodes and sets the Text property of each RadTreeNode to its German translation. This way the user will only see the text changing.
Please write again if you have other questions.
the Telerik team
Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items.