Problem:

How do I set a limit of words to a the WYSIWYG editor (other than with filter cred_form_validate on backend) on the frontend?

Solution:

There isn't such kind of built-in feature within Toolset plugins, the WYSIWYG field is using TinyMCE editor, see their document:

https://www.tiny.cloud/docs-3x/extras/TinyMCE3x@TinyMCE_FAQ/#ineedtolimitthenumberofcharactersausercaninput

There isn't such kind of feature within TinyMCE editor too.

You can setup custom JS codes to send a message to user if they input too much words, for example:

https://toolset.com/forums/topic/cred-field-wysiwyg-post_content-max-words/#post-1903573

Relevant Documentation: