Regarding ‘redo’, I think the problem boils down to Emacs’s undo mechanism - namely that it stores everything (the whole undo an undo). If the undo mechanism were changed to actually remove events from the history (and save them off to a redo list somewhere), then I think ‘redo’ could fit.

But, I imagine you’d then suffer the same limitation all the other undo/redo mechanisms seem to suffer, namely, when you do something other than ‘redo’ after an ‘undo’ you have to clear out the redo list. And then you’ve lost the ability to get back to all the configurations the buffer had…

That’s my thought at least. Emacs’ undo is confusing at first, but I like the power it holds.