In case it helps, for Fedora 30 I did something like:
mkdir -p ~/libremonesetup cd ~/libremonesetup pipenv --python 3.7 sudo dnf install cairo-devel gobject-introspection-devel cairo-gobject-devel pipenv install ldh-client
then searched for the installed nm_tunnel_setup.py and applied the same edit on Line 67 as for Arch (to remove the x86_64-linux-gnu/ from the path to libnm-vpn-plugin-openvpn.so)
CORRECTION: and change ‘/usr/lib’ to ‘/usr/lib64’ as @weswil07 pointed out in a comment below.
After that the following command completed the setup fine:
pipenv run liberty tunnel-setup
Meanwhile, I also found (via https://www.reddit.com/r/Fedora/comments/6m2l5f/automatically_connect_to_vpn/) that you can set up automatic connection to the vpn when connecting to networks that NetworkManager has remembered for you. In summary running
allows you to edit any non-vpn network entry to automatically connect to any vpns you have set up via the General tab.