Language names not in Unicode CLDR
Our new users have made thousands submissions already, so I'm glad to say the survey tool is fine at least for some people.
Speaking of usability, on Firefox it was nearly unusable because of frequent freezes, but Chromium seemed to work well for me.
The CLDR Survey uses too long forms and some browsers have severe problems handling long lists. Things are goind better now that long lists have been split into sublists. But it's true that it is sometime slow, the server sometimes delays its responses to the browwer in a very strange way (sometimes several minutes after the change, and the display is not necessarily synchronized with the input that was done. I also don't like the fact that clicking on an item is moving elements down and up on the page, because of these delays : sometimes this causes vetting clicks to be sent to a non-desired item.
So use the Survey tool with care: it you see some strange behavior, or if it suddenly starts being extremely slow, this is because it has accumulated in the browser too many pending requests (many of them are completed, but the completion event was not received, and these stale HTTP sessions are increasing the number of background threads and sessions up to the point that it may hang the browser (even in Chrome or Chromium).
In Firefox the tool is clearly unusable (let's not speak about Opera...) but the tool works also in IE. The tool lack some developments, it evolves slowly year after year; but Google, IBM and Microsoft should offer more help to the few programmers maintaining it for the CLDR TC. The server side of this tool however is much more stable today and much faster than it was in the past years.