Hi,

> (defun org-table-import-xlsx-to-csv-org () 
>   (interactive)
>   (let* ((source-file  (file-name-sans-extension (buffer-file-name (current-buffer))))
>          (xlsx-file (concat source-file ".xlsx"))
>          (csv-file (concat source-file ".csv"))
>          (org-odt-convert-processes '(("gnumeric" "~/.local/bin/xlsx2csv %i %o"))))
>     (org-odt-convert xlsx-file "csv")
>     (org-table-import csv-file  nil)))
> 
> 
> (defun org-table-import-xls-to-csv-org () 
>   (interactive)
>   (let* ((source-file  (file-name-sans-extension (buffer-file-name (current-buffer))))
>          (xlsx-file (concat source-file ".xls"))
>          (csv-file (concat source-file ".csv")))
>     (org-odt-convert xlsx-file "csv")
>     (org-table-import csv-file  nil)))
> 
> (defun org-table-import-ods-to-csv-org () 
>   (interactive)
>   (let* ((source-file  (file-name-sans-extension (buffer-file-name (current-buffer))))
>          (xlsx-file (concat source-file ".ods"))
>          (csv-file (concat source-file ".csv")))
>     (org-odt-convert xlsx-file "csv")
>     (org-table-import csv-file  nil)))


I copied your suggestions into my init.el file

and tried to export a libreoffice calc file in xml format.

and then I opened this libreoffice calc file in emacs org-mode.
there were unreadably stuff
So may be I misunderstood you.
-- 
Kind regards

Gottfried