The status of Mono in Fedora is sad. We cannot upgrade to the latest Mono versions because we require binary reference assemblies for the build, as described in https://bugzilla.redhat.com/show_bug.cgi?id=1436896#c91
My hope is that when .NET Core and msbuild become part of official Fedora, we can create the various packages for the binary reference assemblies.
For the moment, I create a copr for each Mono version, where we build Mono “the Fedora way”, but with Bootstrap mode always enabled.
So here is the current release Mono 5.18.0.225 for Fedora 29 and Epel 7:
https://copr.fedorainfracloud.org/coprs/tpokorra/mono-5.18/
The sources for the spec file and the patches are here:
https://github.com/tpokorra/mono-5.x-fedora/tree/master/mono-5.18
Mono 5.18 on copr