There are various aspects of this dream.
I'm not that much closer to have this by the move of devtools.
That said, I have been playing around different stats for l10n this
week, and devtools was one of the buckets.
Casting a wider net, SeaMonkey has this problem since its inception, and
we haven't made good progress on this. I had some constructive
conversations with jezdez a while back on making at least
compare-locales/elmo more modular, but that didn't move into a concrete
design to implement.
Long way of saying that I wish we could have this, but I don't have a
crisp set of technical steps to get there.
Axel