The problem is that English and Polish look at determiners quite differently. Polish uses "te/te/tamte" (and its forms) while English uses "these/those/those". That means that "those" is a lot more common than Polish "tamte". Therefore if the Polish sentence did use "tamte", it really is "those ones over there" and only "those" can be accepted.
Are you new to Duolingo? You're not translating a text, where a lot more would be acceptable, where "My father has a very nice brother" and "My uncle is very nice" say more or less the same. You are indeed, in our course, always asked for not only a translation but also a grammatically equivalent answer, if only such a structure is correct in both languages.
We need to check if the learners understand the structure.
Fair enough if true, it should state that then. It doesn't (in this example) it asks for a translation. I've been on duolingo to see moderators accept far worse translations as acceptable. But hey as I've said already its duolingos app and they and the moderators can do what they want, there is after all nuances in language and there will often be disagreements. Asi es la Vida..... Learners can see the comments, see the discussion and come to a conclusion themselves....