rpm -qa '*x2goagent*' x2goagent-3.5.0.34-0.0x2go1.0.git20171111.778.heuler.fc26.x86_64
Ah, now that explains a great deal! You shouldn't be using that package with Arctica's nx-libs version.
What does yum install x2goserver-x2goagent do? If it fails, try running yum remove x2goagent first, then yum install x2goserver-x2goagent.
Mihai