Wiki engines normally save content as wiki syntax (aka wiki text or wiki markup).
WYSIWYG editors such as TinyMCE or CKEditor by default save HTML.
There are some things that are better to do in Wiki syntax, and some things that are better to do in HTML. For example, PluginGroup permits you to show certain content to a group of users and other content to another group. This is impossible to with HTML.
Happily, Tiki offers both wiki and WYSIWYG-HTML, and you can even use both on the same page. This page is to help you choose when you should use one or the other.
Use Spreadsheet and PluginSheet instead. In Tiki9: Use PluginWysiwyg instead for the table; and if Tiki version < 9: Use another wiki page in wysiwyg mode for the whole table, and include it with PluginInclude from the previous page