What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
Unfortunately, you cannot add comments on your form. However, if you have a "Text area" field in your form for the purpose of adding comments on it, then that will work.
In your case, you can view the hidden review section when you edit the submission in your submissions page. Here's a guide about it: https://www.jotform.com/help/325-How-to-Edit-Submissions-Made-on-Your-Forms
Here's an example:
1. Here's my form, the textarea field titled "Comment Section" is hidden:
2. In the live preview, we can't see the comment section. I then fill it out:
3. In your submissions page, when your in edit mode, the hidden section will be displayed. Here's a sample where I added my comment:
To save the edits you made, you need to click the submit button. Please note that email notifications will be resend on this case.
I hope that helps.