When are you asked to translate?
Every day I do a bit of German and a bit of Spanish. When I finish a Spanish lesson, it always asks if I want to translate and provides an explicit button for that. At the end of my German lessons, there is no such prompt.
Is this something I can set somewhere? Or is something else going on?
It depends on the internal barriers the duolingo team has set as the minimum requirements before they start recommending articles. This might depend on finishing lessons from some skill that is considered essential, or their internal algorithm that calculates what percentage of the articles (in a given language) is more than a threshold. I had the same question regarding italian, and when I finished some verb conjugation lessons, it immediately started proposing articles to me, saying that i can read fifty-something percent.
If you are eager to test your skills in german, you can always go to the Immersion section, and start translating any article you find interesting.
There's no barrier to translation. You can translate articles from day one. My understanding is that Duolingo just doesn't want you to forget about the Immersion section and that's why they provide prompts.
Duolingo used to require that you translate in order for a lesson section to turn gold regardless of level. Although translation has always been optional, I think Duolingo took it out of the tree because it may have been overwhelming for early learners. But, a Day One Duolingo learner can contribute greatly to the Immersion section. Of course, their translations are going to be corrected a lot, but a first day learner probably would find English grammar to fix.
I would not be surprised if Duolingo is working on a way to get low level learners to translate, either by providing simplified articles, creating a special tutorial for translation, or something else. My reasoning is that the Immersion section is vitally important to the Duolingo business plan. They want / need us to translate.
I never said that there is a barrier, when you can start translating. My comment is about when duolingo starts to recommend articles for translation after finishing each lesson. And I was definitely referring to the latest duo system as it is now. I also made sure to write that one can start at any time to contribute to the translations.