Pending moderation
If you have forgotten to select the language of translation when you click "Submit translation", the message "Please select the language of the translation" in red will appear under the "Translate to" box, but instead, if you click "Save translation draft", you're shown a page saying:
"Error
The website encountered an unexpected error. Please try again later."
It would be better if this too produced the red instructional message, since it's not an unexpected error and trying again later would give exactly the same result.
Fixed, thanks for reporting.
By twice forgetting to select the language of translation today, and subsequently having people ask me what the the mysterious "Unknown" language I have translated to is, I have realized that this feature I mentioned in my old post has been removed. Was this intentional? I wish it to be reinstated, because it has helped me a lot in the past. :(
After further investigation, it seems to me that if we forget to state the target language and publish it at once, then we get the red error notification. But if instead we first save it as a draft we'll see the draft with "Unknown language" set at its language, and if we then click "Edit" and "Save and publish", it will be published set to "Unknown language". Please try this sometime to confirm it's not just I who have this problem.