With ckgedit you can copy and paste a spread sheet into the editor. Before doing this you have to
Turn supplementary image paste support off. The table will be editable and rows and columns can be added and inserted. But It will be a 'dumb' table, that is it doesn't know how to do anything but display. You can, however, paste new data into the table.
For an example, see:
https://www.mturner.org/devel/playground/copy_tables