Welcome to the forum.
You are asking about the search but pointing to index issues.
Which is it, or are both giving problems?
Does the help compile and do you get anything in the index
frame? Does the search work and if not what happens there?
Does everything display correctly in the topics and the TOC
and index when you are working on the project?
Finally, open one of the supplied projects in English and see
if everything works there. Alternatively, create a new project in
English and try that. It will establish whether the error is
language related or an installation issue.
Let us know on those and maybe it will trigger a thought.
Help others by clicking Correct Answer if the question is answered. Found the answer elsewhere? Share it here. "Upvote" is for useful posts.