Kiwi TCMS does not and will not support import and export functionality to/from Excel, XML, CSV or other formats!
Use the API to create your own import/export scripts!
When importing historical test data from other systems your input files may contain arbitrary information, whose organization and meaning is known only to you! There’s no way Kiwi TCMS will be able to reliably guess what that data may be and how to interpret it.
When exporting machine readable formats are used to facilitate integration with other software. Again Kiwi TCMS has no idea what information and organization behind the data is expected on the other end!
XML, CSV, JSON are machine redable file formats which are not designed for human consumption so this is not a compelling reason to add support for them!
Example(s) how to use this API can be found here.
Further information can be found at Kiwi TCMS Python API client and https://tcms-api.readthedocs.io/en/latest/modules/tcms_api.plugin_helpers.html.
Please be a good open source citizen and share your import/export scripts with the rest of the Kiwi TCMS community. You are welcome to do so by opening a pull request at https://github.com/kiwitcms/api-scripts.
Alternatively you can develop your customized import/export as a web application and distribute it to your users as a Kiwi TCMS plugin.