"We need the names of their mothers and fathers."
Translation:Potřebujeme jména jejich matek a otců.
It is! But in this sentence, we need the GENITIVE plural (OF their mothers), rather than the nominative. And... that would be "matek."
Two reasons. The course sticks to formal "mother= matka" and "father = otec". You can get mom and dat and in such a case we go for máma a táta. The system does not have diminutives at the moment.
The second one is, even if we did accept 'tatínek:, nobody would ever mix it with "matka". Once you use diminutive for one, you use the same for the other, because it just simply sounds funny.
Potřebujeme jména jejich maminek a tatínků....
Can't "the names" be "ta jména"? Use of adjective in accusative case from earlier lessons.
Strange. Not completely impossible, but unnatural. I would translate that using "those", not using "the".
Translate the whole blocks, not just individual words and certainly not individual articles. "the names of their..."="jména jejich..."
Regarding word ordering, why is "Potřebujeme jejich jména matek a otců" wrong? (We need their names, Mom and Dad)
Their/Jejich belongs to the fathers and mothers, not to the names.
We need their names, Mom and Dad. is a completely different sentence.