There is an emacs mode/plugin called Proof General which almost all Proof Assistant can use (and some practically require). That was a barrier to entry, certainly, getting used to emacs editing conventions. So I'm not surprised a jEdit alternative came about. For many years, jEdit was by far the best emacs alternative with modern CUA conventions (these days, I got to admit VSCode is hard to beat).
[1]: https://isabelle.in.tum.de/