Glad you're enjoying and finding CT useful :)
This is planned on our roadmap, but it's not currently milestoned for any particular release. Given it is a free plugin, we can't dedicate the time to it that we would like.
We do think it is the last feature that would make Clean Testimonials truly powerful, so it is definitely important to us.
Instead of allowing the user to edit the default form, we are considering giving users the ability to completely override the form by replacing it with a Gravity Form, a Ninja Form or their own form entirely.
If you would like to help fuel development, please consider a small donation or leave us a rating that you think we deserve :)