There is a problem with the quotation system, and the leagues
When you start a language, the first lesson need about 10 right answers to obtain 10 XP (+5 if you are all correct). When you are advance in a language, it needs you 20 or more to obtain the same amount of XP. The problem is that we are all mixed in league, newbies and advanced learners. The stories are quite simple to validate and you earn 22 to 24 XP if you make it without errors.
It encourages people to start new language to make more XP and not to improve the language they generally come here to improve.
It would be fair to give the same amount of XP for the same number of correct answer. Whatever the level.