Javascript Validation - Documentation?

Super frustrated - I’ve wasted many hours searching for threads and any information I can find on how to programmatically work with the Unbounce validation plugin. How exactly do we do things like showing the validation error for a field that has failed validation from an ajax server call? E.g. the form data is sent to the server, and one or more of the fields fails validation on the server. How are we to show the errors on the fields client side? I find nothing…