Can people actually write in a full sentence instead of one word? For example these and are classified as "Nonconstructive Reply"
(I assume you mean 3.2.0) Look into this FormAPI PR to see an implementation of it. It's pretty straightforward, you need a class that implements `pocketmine\form\Form` and gets JSON serialized into the form data. Then you use `Player::sendForm()` and pass it your form instance. In your `Form` class, you also need a `handleResponse` method. For a `custom_form`, either an array with the response data or null if the form was closed will be passed.