xdass when custom domain is renamed
So, when you change your custom domain? But that's something that you should be able to do - we can't redirect from your old domain, because we do not own it.
If you mean redirect on forum name change, then that's not possible either. That's why we've put a warning to "think twice before you rename your forum". In other words, "rename at your own risk and don't forget to notify your users before you do so". Yes, we could probably implement a system that will redirect users from the old forum to the new one for some time, but it's not as easy as it seems and it would require another time to develop.
If you're really brutal though, you can rename your forum and register a new one with the old name. Then, write a simple JavaScript to redirect users to the new forum, eg.: window.onload > window.location bla bla bla there are tutorials on the internet and delete the forum after some time. But I do not recommend doing this because it's a brutal and useless, overcomplicated workaround.
If you mean when you simply link your custom domain for the first time and redirect users from FreeFlarum's domain to yours, then I am pretty sure that that's a thing already.
