I had the sentence to listen too, and the first time did not check the slow, because it seemed evident that it was "mówi o nich" the ę is heard only in the slow version. Is that normal, I guess in a conversation it would be clear who is speaking. I would like to know if the polish are dropping the last syllable, and when. thanks.
No, Polish generally pronounces everything that is written, apart from really few exceptions (and pronouncing final -ę as -e). So absolutely no syllable dropping.
I think I can agree that the female voice sounds more like "mówi" and the male one at least could be mistaken for "mówi". I disabled the audio exercises, so at least no one will get the 'type what you hear' exercise.