Hello,
I'm sorry, I'm lost with this.
- When you say "update your CNAME to point to cname.freeflarum.com", you mean "cname" in the url must be replaced by our freeflarum name? Because in my host, the CNAME redirection already points to a "cinstudtest.flarum.com".
- And what do you mean by resetup the domain?
Sorry, I'm must be slow on this but I wouldn't want to broke anything...
If it helps, for now my redirection host looks like that (forum.cinestudia.fr being my desired final url):

And the freeflarum settings looks like that:
