Special characters are common in many languages. Such as Norwegian, Thai, Swedish, German etc.
If you're using Microsoft Excel or Mac Numbers, Please make sure to export your files with UTF-8 encoding. Else your special characters will not be exported correctly, and Keyword insights will show you an error.
When possible, we highly recommend you upload an excel XLXS file when dealing with special characters instead CSVs. The CSV encoding can convert special characters into random unreadable text, and it will cause our clustering and hub/spoke algorithm to produce incorrect output results.