Does the mandarin course ever ask for voice input?
On the Spanish course you were required to verbalize words, which is how I learned them fast. I'm on section three (names) and so far, no voice input and really, not much translation either. Its mostly just match the pinyin to the characters. Without saying the tones and practicing them, its really kind of limiting. Does that come up in later lessons or are there plans for that in the future?
You could try another app - ChineseSkill (altho I am also not a lover of too many apps for the same thing), but it has tonal exercises and offers voice input which gives you an approximation of how correct you are and what word was not pronunciated good enough if it was a sentence. I find it also has a very good breakdown of tones and pinyin. It has a LOT of differents resources within it, so maybe try it? I am currently using both that and Duo.
They apparently do not and I can understand the reason: current speech processing technology is not good at recognition of suprasegmental phonemes like tones, stress, and length . Suprasegmental phonemes takes value that are relative to nearby syllables and currect computer perception technology cannot process this relative value; in fact, computers have difficulties in recognition of the same segmental phonemes (consonant, vowel) in different tones and stresses.
As 5g has said, I would highly recommend speaking into Google Translate to test and adjust your pronunciation. The app HelloChinese also has an excellent pronunciation practice feature, giving you extremely precise feedback on every word in sentences you say. All the other resources that have been mentioned on this thread are solid as well!