I agree that document translation is necessary; however, Kagi's staff currently can't cover all languages. Currently, users who love the service (including myself) are voluntarily doing the translation work without compensation.
The search project (including Assistant) already contains 3,700+ strings. Adding documentation on top of that would be too burdensome for newcomers (especially if their language hasn't been translated by others yet).
Given Kagi's current scale, I suggest using Kagi Translate, perhaps by suggesting users use the tool or by providing fully machine-translated documentation.
Edit: Rephrased for clarity