This is fantastic!
my first thoughts in the "UX" department
I've found on-screen prompting helps a bunch with UX. The issue is we never know where to look on the screen, exactly, so using a sprite or other callout on first load does wonders for lowering cortisol.
Animating the text after 'run' will also give people's brains a chance to process and add some 'liveness' to the experience. Can also be a 'first-run' thing or a 'second click prints immediately' thing or 'every other click prints immediately' thing.
What's always fascinated me about devs, generally speaking, is that everyone says "code should document itself" but then everyone talks about how hard it is to reason through code...
The general rule of thumb is "5 +/- 2" to estimate the number of items a person can hold in short term memory/attention. Also, everyone has limited "decision juice" (that's the official term) so later in the day people's ability to decide will be stunted. (that's why nobody cares where you go for dinner, btw)
On the more complex examples, adding a stepwise UX can help reduce cognitive load.
For example, the union type has 4 classes with 7 types total (that's an ass-load of combinations)
So the person is not quite sure where to look to 'map'.
Highlighting the words can help (brains match colors super fast which is why Toyota uses colors in their Kanban boards and tickets)
Try it yourself, on the Union type put NeedsMoreInfo into the search box and see how much faster you can find what you're loooking for.
{{ General comment: the height is a bit off so I've got to scroll to get to buttons. I'm sure you're aware but it can be easy to scroll when you're coding a site and forget users don't like it)