Is there a way to search by known words %? The only thing I can see is the new words% but even if a lesson had a reasonably low new words percentage, it could still have a lot of LingQs in there too, so the known word % will be a lot lower than you expect by simply taking the new words % from 100.
At the moment it’s not possible to sort by Known Words %. What you can do is to sort by New Words %, and the less this percent is, that means more Known words (or LingQs) are in a lesson.
This means that turning words yellow can make the course disappear from the filter view which may not be that helpful, so I turn fewer words yellow. It would be userful to be able to filter and sort by % of not-known words.