I'm currently close to finish the Spanish course, with just the legendary levels of Unit 10 (from the old tree, which I still have), which I'm guessing are now at the end of the new layout.
These are obviously one of the newest bits of the course and it's very clear that they haven't got all the correct synonyms and alternatives set up yet which is enormously frustrating (especially so as it's often the British english synonyms that aren't in place yet). I'm reporting all my 'my answer should be accepted' mistakes....but anyone know how long Duo normally takes to improve things like this?