A reply to the reply here. I was able to get it working on my Fedora Toolbox environment by adding two symbolic links:
sudo ln -s /usr/lib64/libcsound64.so.6.0 /usr/lib64/libcsound64.so
sudo ln -s /usr/lib64/libcsnd6.so.6.0 /usr/lib64/libcsnd6.so
I think there are issues that the dnf install csound did not handle for me. The Fedora environment tries to lock down many directories, moving towards a read-only file system with containers for all user activity. The Csound install in this environment didn't make the symbolic links, perhaps because the install did not have the right permissions. I was able to see what was done in the Ubuntu container, then copy the missing files to the Fedora Toolbox and then I could make the symbolic links.