I'll submit a patch for this, just a script somewhere in puppet and a cron to be run on terbium or fenari (wherever noc.wikimedia.org is).
Main things I need to figure out:

• where to take the list of wikis for which to run the script (probably better to focus just on the main multilingual wikis);
• where to output the text exactly: probably, the home of the user running the script, à la https://noc.wikimedia.org/~reedy/ .

I'm told the unit of the counts is unclear, but that doesn't matter much as long as the counts are (directly) proportional to the activity (or more specifically, as long as the relation is monotonous): we only care about being able to compare how well we're doing compared to the past.

This sounds like a good idea.

Change 117250 had a related patch set uploaded by Nemo bis:
Add cron job to run characterEditStats.php on multilingual wikis weekly

https://gerrit.wikimedia.org/r/117250

Change 117250 merged by Alexandros Kosiaris:
Add cron job to run characterEditStats.php on multilingual wikis weekly

https://gerrit.wikimedia.org/r/117250

I also created an explanatory header. https://meta.wikimedia.org/wiki/Meta:Babylon/Translation_stats/Report
Closing for now, we'll see in a week if it works. :)