The TTS engine is not having enough delay between words (especially between "Ale on"), and it sounds unnatural. I've heard and been in conversations with speed speakers, but this is something completely different. Duolingo needs to take a beat longer between words, even for fast speakers.
I am not an expert on this, but some of these phrases(and words) seem a bit unusual for basic Czech. I thought more familiar language would be easier to start with. But maybe this approach is better?
It seems common to have discussions like this for unusual phrases and non typical words. For our levels of Czech, I think it would be better to use standard phrases and words to reduce confusion. I appreciate the CZ course, I just want to help. Hope this is the correct place. :-)