Nicolas, I'm concerned about this - particularly as you need an activated translator account before you can see the system UI. If you have specific things that worry you please bring them to our attention. We would rather address problems than evade them
One of the bugs in the new translation UI is that you can see the string-translation UI and use it without an activated translator account — and then get an error when submitting it.
And one of my hates about it is that it's a "web app". There's nothing you can do about that :)