About Special:Translate in MediaWiki extensions
Did you change the order of message groups in Special:Translate?
"Show all messages" doesn't work.
It may be disconnect some Wikimedia servers. Then not support current in Wikimedia Messages (e.g MediaWiki, Wikipedia Mobile, etc.). Other than that, all messages is supported.
Don't worry, messages are not lost. I filed bugzilla:40413, it will be fixed soon.
Thanks. Now Special:TranslationStats also works correctly.