https://kate-editor.org/get-it-kde-4-x/ (not working anymore)
https://kate-editor.org/build-it/
https://invent.kde.org/kde/kate/tree/Applications/14.12
If it does not work, get the tar file:
kde-kate.tar.gz
Install Kate from source, and for your use add the alias:
alias Kate='~/kde/run.sh kate'
Then on the open line type something like:
fish://[email protected]/afs/cern.ch/user/a/amassiro/test_file.txt