"Con chim sẻ chia sẻ bánh mì."
Translation:The sparrow shares the bread.
Yes, the hỏi tone here sounds unclear. I think the vowel e has affected the quality of the tone. In Vietnamese standard voice, the e sound is /ɛ/ while this speaker pronounces e nearly like /eə/. This vowel deviation makes the word last longer and the hỏi tone is protracted. That is why it sounds a lot like the huyền tone.
Generally, tones are pronounced almost consistently. Of course, there are some small deviations but they're rare.
I feel that a lot of the content on the vietnamese program has been designed to trip you up on individual tones and syllables. I suppose it hones sensitivity to the relatively minute differences in form that more often than not do not carry to meaning.
With that said, it's just maybe not the most optimal, practical, nor the most motivating approach to start learning a new language.
It's not useless at all. Have you read the story of Andersen? To the best of my recollection, that story is "the girl and the bread". The girl was bad and she was punished in the hell. But later she felt regret and became a little sparrow, the little sparrow was not bad anymore. The bird shared the bread with the others on the street.