What does any of this have to do with KDE, Gnome, or nautilus? If symlinks aren’t working, I’d dedicate an entire drive to Steam by mounting that drive (with matching permissions) right where Steam expects to find them. You can mount a filesystem/disc/ISO/drive/network share practically anywhere you want. If your network is fast enough, I bet you could even access your games over NFS, though I wouldn’t recommend it.
What does any of this have to do with KDE, Gnome, or nautilus? If symlinks aren’t working, I’d dedicate an entire drive to Steam by mounting that drive (with matching permissions) right where Steam expects to find them. You can mount a filesystem/disc/ISO/drive/network share practically anywhere you want. If your network is fast enough, I bet you could even access your games over NFS, though I wouldn’t recommend it.