Really good addon, we use it quite frequently and have almost no issues with it. Some a bit hard to tell (such as Form Cooldown, did not know it was global rather than per user) but do have a suggestion!
It would be nice if there was some advanced customization, for example, utilizing APIs. If for example they enter a username, we could add an API to this and ensure that the username is valid, if not, a form error would produce to the user.
Regarding errors, perhaps delay them on the form instead of on submit? Especially when it is difficult to ensure that they are aware what kind of question, could be beneficial.
A "Next" form! So essentially, kind of like Google Forms, you have sections. For example "About you" section could ask Name, Age, Experience and then they can press next.
(not sure if you take suggestions, or ideas, but might as well!)