You've seen the worst side of Duolingo. Duolingo is rubbish for learning most languages, but the Russian and Ukrainian courses are particularly bad.

Not only do they not really teach you the Cyrillic language foundation, but they don't teach cases and tenses. The whole course is trial and error until you learn the handful of phrases they added in.

I think French and Spanish are the only courses on Duolingo that even give proper teaching, probably because they cover most people (Spanish for US citizens, and match up with US/UK school language curriculums). The rest of the languages have much shorter courses, with less content, no teaching, and poorly structured courses, mispronunciations.

My Russian other half forbade me from learning her language with Duolingo.