Well, I'm sorry, I can only help so much. I also try to open source many things as I can, and I'm active on Github in many projects but I have only so much time.

> Some of these (keyboard nav, focus) we test for and sounds like a specific issue with your browser/OS setup

It's probably not (tried on another computer and browser). Please open this page: https://perspective.finos.org/blocks/superstore/index.html Try to navigate with your keyboard. There are no outlines and the tree view is not possible to interact with.

> I'm not aware of any label+input in the component

The top and right toolbars here: https://perspective.finos.org/blocks/editable/index.html Are the not the part of the component? Perhaps I'm mistaken to think so. My apologies if they aren't.

> how column selection is related to accessibility

https://developer.mozilla.org/en-US/docs/Web/Accessibility/A...

The column headers aren't possible to interact with a keyboard anyway, and the screen reader doesn't announce anything to indicate that the table can be sorted.

In my current job, we paid a lot of money for an army of auditors to hunt these down for us, and I don't expect that you do something like that for an open-source product, but if you have corporate use (I mean if people are paying for this directly or indirectly, and I hope they do!), maybe it makes sense to go for one?