The raw score is simply the sum of alternation and reach. Without research into whether alternation or reach matters more in the long run, I don't feel like I can provide an aggregate ranking.
Regardless, we can draw some rough conclusions like Dvorak is best on alternation, Colemak is best on reach, and they both blow Qwerty out of the water.
EDIT: Even though more alternation is better, the numbers above represent effort, meaning subsequent keypresses with the same hand, so lower numbers are always better.
As far as contributing goes, if it's possible to reliably support non-ASCII characters without special knowledge of the user's OS config, please take a crack at it (or at least open an issue). Thanks!
I wouldn't say alternation is always better -- in many cases, having successive keys close together is just as good if not better - "There" the first three letters "The" are typed with alternate hands, then the next three - "ere" are also easy to type fast because they're to each other.
I haven't used a dvorak keyboard, but the next to each other keys are really a part of my flow. I really don't know how "<esc>:wq", "<ctrl>a" and so on which are part of programming work would translate to dvorak.
I think you have a good point in that working in "command mode", or "chording", or whatever you want to call it, is different than writing prose. FWIW, I am a Vim user and I think it works great in Dvorak (https://news.ycombinator.com/item?id=4323873). `<ctrl>a` is the same as qwerty, `:wq` is typed on both hands, but as I say in that link, I prefer split hands for `hjkl`, and `wq` is pretty easy too.
To your point I would accept that in command mode, key position, mnemonics, etc. may be more important. In insert mode however I think it is, at the very least, a sound hypothesis that more alternation creates more comfort.
Also, I might be interested in helping you get this to analyze non-ASCII texts.