Yet another round of fixes for the translation server.
fixes have been merged & deployed.
i'm not sure what you mean about the langs.json file, it seems to be there?
$ ls /var/lib/weblate/scripts/langs.json
okay another point for typos in filenames - I missed the ending "s" and checked several times against lang.json before.
I added this fix and two other fixes on my hefee/dev/translation-server branch. Please merge.