The "many UI" problem is large in Rust. Egui needs far too much Rust code per dialog box. Someone was working on a generator, but I haven't looked in on that project in a while.
I actually quite liked egui. It was Rust that felt too slow to write. Also the egui template project with eframe and no app code yet took 15 seconds for an incremental compile. The entire game so far compiles and starts faster than that in Java, so...
The "many UI" problem is large in Rust. Egui needs far too much Rust code per dialog box. Someone was working on a generator, but I haven't looked in on that project in a while.