Actually found the solution!
When working with LibreOffice it is mandatory to save the file with the "Save As..." option and, in the Save As dialogue, additionally activate the option "Edit filter settings".
After hitting "Save" it will ask you to confirm the file format. Hit "Use Text CSV Format" and in the next dialog you have to select the
Character set "UTF-16" (Character Set of the original file)
and [TAB] as field delimiter. Hit OK and .zip up the file.