Thanks for the heads-up. Unfortunately the implementation of theme-creator has proven extremely hard to maintain, especially with all the changes happening in the core theme / color-palette systems right now.
We do have a medium-term plan to overhaul it. The idea is that we could allow regular users to access to the theme section of the admin panel, on the normal admin panel URLs. That should be much easier to maintain than the current strategy of totally re-implementing the theme system under the user profile.
That said, we’ll keep trying to patch up the smaller issues like this on the existing system for now. I agree not being able to edit titles is pretty critical 
Of course, PRs to help keep things working are always welcome at GitHub - discourse/discourse-theme-creator