https://wordpress.com/start/upgrade/user
During signup process, if a user enters an already existing username, the English version shows this error message:
Sorry, that username already exists! If this is you log in now.
For non-English, a partial error message is shown: only the translated version of Sorry, that username already exists! (no option to log in for existing users).
Confirmed the issue in DE, FR, ID, NL, RU locales. Likely a global issue for all non-EN locales.
Google Chrome 48.0.2564.109 (64-bit)
OS X El Capitan 10.11.3
_English_

_French_

Confirmed this is still broken, testing the signup flow in Spanish:

Missing the
Code ref: https://github.com/Automattic/wp-calypso/blob/9cb2557484fc059ab3af01be5de03e913770abf1/client/components/signup-form/index.jsx#L293 — looks properly coded with the translate call.
This requires an API change, tracked on D1793-code. It should work automagically after the fix is released.
The change is live and the issue should not be occurring anymore. @lancewillett Can you verify that?
Confirmed worked as expected! Nice.
