So far, the webform only allows to export the survey into xls or xlm and to import from xls.
A nice additional feature would be to permit the export/import from .ods (Open Document format, used by LibreOffice). Indeed, this file format is more consistent (zip file with xml files in it) and does not requires Microsoft Office suite to be edited.
Also, the xls format is old and even recent Microsoft Office suites suggests saving the file into xlsx (not supported by KoboToolBox neither).
To balance this suggestion, I am aware that LibreOffice can quite well import xls file and therefore, I do not believe this new feature be urgent, but nice to have.
I would be interested reading your opinion on this.