Why so little English-German translation?
The type of task that is most challenging and most tests mastery of the material is the translation of English into German (L1 to L2). I haven't actually counted, but this type of task seems to occur the least in both skills practice and in the modules, with much more German-English translation and transcription of German speech. Why is this? Do the proportions change as we move up the tree?
Just a tip: You could try taking the reverse course to practice English-German translation! While you can't do it for languages like Esperanto which don't have a reverse course, you can do this for extra practice in the languages that do!
As Popp2 suggested, try doing the reverse tree if you want to start practicing English to German.
I wrote the very same thing a few days ago about Norwegian course and I was answered that they (the volunteers that create the courses) can't do anything about it, it is beyond their control.
in the current system, Duolingo will penalize harder sentences, so they don't show up often. because EN→DE is harder than vice versa, these get removed from the course. yes, for now, we can't do anything about it, but Duolingo knows about the problem, and we'll probably see a fix for this some time in the future.
What is the rationale for this? Isn't spaced repetition based on the opposite principle, i.e. that material we find difficult requires more review, while easier material requires less?
The rationale was that hard sentences might be bad ones (faulty/unnecessarily complicated). But Duo staff became aware of the problem of only serving users cake all day, and this problem will likely be tackled in the foreseeable future (no idea on when though).
me too, but there might be problems down the road: