"A human has ten fingers."
Translation:Człowiek ma dziesięć palców.
True for Polish, but in English the other ten are called toes, so it is a bit of a problematic sentence to translate.
We're teaching Polish here. Accepting "10" contradicts the whole idea, because then it's as if you didn't have to know the word "dziesięć".
It seems you are not teaching, but enforcing your own rules. In all Duo's courses the digits are accepted, seldom not. Consistency is the key in learning. Are you thinking now to remove digits from all course?
Sorry, but... "consistency is the key to learning" is probably the most nonsensical phrase I have heard in a while. If being consistent means to consistently look for the easy way out, then this won't support your learning, it will impede it.
The contributors of Polish from English don't have access to all the other courses. And I personally don't care what the Chinese or the Klingon course accept and what they don't. Polish numbers are tricky (especially their pronunciation and inflection). It's important to take them seriously.