I find it a bit frustrating with all the pre-mutated words. Could this be fixed in the app?
These have already been deleted from the course database as a result of feedback in beta testing. Unfortunately, a long-standing bug in the Duolingo system means that deleted phrases turn into zombies - they keep appearing to learners. There is also no facility in Duo for a course team to edit the target language phrases - we have to delete them and start again, which leaves us with the zombie sentence plague...
Check that you have the latest version of the app - there are fairly frequent updates and perhaps some of the zombies may disappear from more recent versions.
(As it happens, arddwr means 'ploughman'. )