A couple of problems and comments:
1. When enabling debugging you need to set X2GOBROKER_DEBUG=1 in /etc/default/x2gobroker-daemon, but this isn't specified in the file. It should be in the file, just commented out or set to 0.
2. Where you need to set the key file, it says X2GOBROKER_SSL_CERTFILE where it should say X2GOBROKER_SSL_KEYFILE.
3. Because the daemon is started as a non-privileged user, it is not possible to use ports below 1024 on most modern setups. That means, that port 80 and 443 is not possible to use. The daemon needs to be started as root, grab the port and then switch privileges to a non-privileged user.