What do you use the other 25% of the time? Anything in https://lispcookbook.github.io/cl-cookbook/editor-support.ht... ? I've never used Kate before now, but I gave it a spin. Seems you could use it for some primitive Lisping (certainly to just teach yourself the basics, or make edits to existing programs), but I wouldn't recommend it long-term. A big win with Lisp is in interactive development, so you want an editor that supports something like Slime -- particularly the ability to have a running program and interactively run code, which might define new functions or redefine old ones or change some state, whatever, and have such changes immediately take effect.

I suspect a plugin for Kate could be made, but I didn't see one after a very brief search. The maintainers probably want to encourage more use of LSP anyway. There is an LSP server for Common Lisp, but it's pretty basic, and is still at odds with how you want to do things. (Perhaps Clojure has a more developed one.) It at least "works" with Kate in the sense that Kate successfully launches and talks to it after making a custom settings.json, and gives me simple symbol completion and docstrings on hover. But to learn about my own functions and their docstrings, I need to be able to load my code into the Lisp instance that's also running the LSP server. (Traditionally IDE-ish features in Lisp aren't done by external tools statically scanning files, but by introspectively asking the Lisp program itself for the info, which may include file info.) I did hack something together so that I was able to copy-paste some code from Kate to the split terminal panel running a second instance of Lisp that talked to the one Kate launched, but this isn't very productive. You could maybe get by with writing some code, saving, and then reloading the whole set of files (system) with one command when you want, but you'd need even more work to make errors interactively recoverable, which is another really nice feature of Lisp development when you have proper editor support.