Having created JavaFX apps in the past: that's comparing mopeds to racecars, because the actual code writing part in JavaFX is so much more tedious. The upside of moving fast and breaking things (which you're absolutely going to with a webview app) is that you move REALLY fast, and breaking things is almost trivially fixed because everything lets you either look at the dev console directly, or attach a dev console in seconds, and off you go setting your breakpoints and var watchers.
(and as always, how bad you break things and how quickly you can determine where and how to fix it has nothing to do with the choice in tech, and everything to do with your experience as a software engineer, or "dev" as we apparently call folks these days)
More tedious than HTML? That's a surprise. Java is more verbose than JavaScript it's true, but I've been using Kotlin for years and Kotlin is more concise than both. HTML doesn't even have much of a widget library beyond a few basics, so to get even close to the basics JavaFX provides you need to import a whole pile of libraries.
I'm curious to learn more about the dev console thing. The dev console is a nice thing but you're talking about breakpoints and watches. Any IDE has a great integrated debugger, and with JavaFX you can step into the entire GUI framework right now to where it issues draw calls to Direct3D or OpenGL, so it's far more debuggable than a webview. I would understand more if you were talking about things like the network explorer views, but debugging? Java debuggers are great!
(and as always, how bad you break things and how quickly you can determine where and how to fix it has nothing to do with the choice in tech, and everything to do with your experience as a software engineer, or "dev" as we apparently call folks these days)