Fine for spoken language but it should be “darauf” in written form.
It’s listed on leo.org and duden.de, and I see it frequently in casual written speech. Tatoeba, and Clozemaster, don’t just teach formal, textbook German. If you want to learn German, you’re going to want to learn these casual contractions because you will see them, and you may come across as more natural if you learn to use them. Nowadays, with the internet and social media (and Germans are pretty active on these) a lot of these casual forms are explicitly written out.
You are right, but the “darauf” should be also accepted. Why is there only one good solution here?
Only one answer being accepted is inherent to how Clozemaster works. If you want multiple answers to be accepted, maybe try Duolingo. Personally I strongly prefer Clozemaster to Duolingo now, especially after the major changes 4-5 years ago that effectively broke Duolingo for me. I liked it much more before that.
Back to Clozemaster, it’s useful though to be aware of multiple valid answers, which is why these talk pages are good.
You can use the color-highlighting as you type the word to avoid making mistakes by typing in another valid word.
I personally find Clozemaster forcing me to recall other words to be useful because it makes me learn multiple spellings and/or synonyms.
I repeat that this system (Clozemaster) ist the worst way for leanring a new languge. The load of totally unrealetad street (and often vulgar) jargon just put mess on language (German) that is extremely complex in her struture
@Enrico_Pirani thanks for the feedback! We’re always working to improve Clozemaster, however his phrase is actually quite common in German (though darauf should be accepted like @nagyandrasgeza suggested).
It seems like you’ve been posting a lot of negative feedback lately. We’d be happy to give you a refund and cancel your Pro subscription as well as recommend some other resources that might be a better fit. Please feel free to email me at firstname.lastname@example.org if that’s what you’d like to do.