Game engines (at least the lightweight ones) seem good for cross-platform graphical apps in general but the idea of redrawing a static GUI at 30 FPS just sounds too inefficient to me.
We're all up this tree where we want all the features we're used to and we're willing to put up with software bloat and insecure software and sprawling supply chains to get it. I'm not. So I start with something minimalist and do what I can within it.
One of my inspirations is http://akkartik.name/illich.pdf
Is it an artificial limit you put on rendering?
Do you have button animations at 30 FPS?