the audio does not have an intonation of question
Unfortunately no. There is nothing we can do...
Well, maybe you could change the sentence to “Umíte anglicky!” (Speak English!) to match the intonation. ☺
That would be completely wrong. Speak English! is Mluvte anglicky!
May I ask "Mluvíte anglicky?" as "Do you speak English?" or will it be incorrect? Not in terms of this exercise, but in general