Unfortunately, it appears you have come across a know issue/bug, still open, with the current version.
See these issues:
https://github.com/warpech/jquery-handsontable/issues/751
https://github.com/warpech/jquery-handsontable/issues/464
Try removing the language option if you don't need 'de-de' as this seems to work for me. Otherwise, you could possibly try your own custom column renderer, or similar, as a workaround.