Oh right, that was an old doc, sorry.
See "For CKEditor versions older than 4.6 the following options were available, too:" @ https://ckeditor.com/cke4/addon/pastefromword
According to this page https://sdk.ckeditor.com/samples/pastefromexcel.html
the plugin is available in the newest version (4.7.x) which will also be used in OTRS 6.
Try modifying it or wait for a stable v6 release, but either way, it's a CKEditor, not OTRS problem/feature.