I decided the latter opinion was the one I cared more about.
I'm admittedly trying to play it very safe. I have zero proficiency with screen readers, so I'm not really able to independently verify any of this. All I know is that the GUI toolkit is one of the most expensive things to have to change later, so I want to be as close as I can possibly be to 100% sure that I won't end up in a situation where my projects have accessibility issues that I can't fix without changing the GUI toolkit.
From what I've read, JavaFX apparently has its own accessibility problems; for instance, I vaguely remember reading that if you used Alt+Tab to switch to or from a JavaFX window, JavaFX would automatically activate the menu bar. I've never used a real JavaFX-based app though.
As much as some of us might dislike it, I think the safest choice is Electron, or just making it a web app if that's an option.
Electron does have its downsides. On the upside, one nice thing about making screen reader support non-negotiable is that it took so many options off the table. So I was at no risk of analysis paralysis, and I don't have to worry about second-guessing my decision.
Neither have I; from what I can tell, the only place that JavaFX seems to have a foothold still is "intro to software engineering" classes in colleges.
That's not nothing. Blind students need to be able to participate in those classes.