I can’t speak to the API side of things, but I can comment briefly on this:
The field setup dialog size is determined by your window size. If you’re on a small screen, like a laptop, the field setup dialog compresses a bit, with rollup fields suffering the most. You can get a little more real estate if you run your browser (or the desktop app, whichever you’re using) full-screen. You might also try increasing your desktop resolution.