If the Ardour package doesn't work out of the box, I think the place to start is filing a bug (or bugs) against it.

I'm no expert on PulseAudio (my only advice is that in Xfce, you MUST install https://apps.fedoraproject.org/packages/pavucontrol), and I know nothing about Jack, but I bet there are plenty of Fedora users out there who have experience and tips to share on Ardour.

Ardour itself is working fine.

What I'm trying to do is, at least, raise awareness about bad out-of-the-box integration between PulseAudio and JACK in Fedora Workstation.

Anyway, thanks for the tips :)