While that might be possible using the ObjC bridge, it’s probably not very nice, either.
Personally, I try to avoid AppleScript since it’s so old and sub-par compared to current languages. But if you’ve already written smarting large in it, there’s no point in changing.
Oh, they did. But it’s even worse than the usual documentation they provide.
Well, if an error occurs, you get a message. Much like with AS. But you’re right, there’s no debugging possibility except for console.log.
Or using node_automation in node.js, which has seemingly a better integration with the OSA than JXA does.