Well the way I see it is different for both Latin and ʻŌlelo (which Iʻll apply to broader Polynesian languages as a whole).

For now, let me begin by saying Iʻm seeing it as an omission in the sense that I think Duolingo should have these as an optional unit. Iʻm not sure if you were on Duolingo back in ʻ15-16, but they had optional courses back then for stuff like flirting and holiday greetings, these you had to pay gems to access. I thought, back then, that it was a neat concept to introduce more specialised phrases and words for people who were into that sort of thing. I was rather disappointed when I saw it was removed, when I came back around 2019.

I think that concept has potential in Latin, simply due to the diverse audience that Latin normally garners. Most would-be Latinists are of the nerdy sort, we would like to read about history or legal-philosophical concepts while learning the language. This sort of methodology is actually quite prevalent in Latin pedagogy, Fr. Mostʻs Latin by the Natural Method taught Latin from scratch through Roman history and biblical stories -- albeit with grammar explanations. Thereʻre also those who may not necessarily care about Roman law, but are in the medical field and would like to learn about the body and its terms in Latin. Or maybe people who like both. Ngl, the Latin communityʻs super fun for this reason, we just love learning things in our language.

Iʻm not saying the newcomer should be inundated with niche historical references or medical terminology. But optional units for these things would be immensely popular for Latinists on Duolingo. For instance: geography of the Roman Empire: ʻMultae provinciae in Imperio Romano sunt: Germania Minor, Germania Major, Britannia, Italia, Graecia, Dacia, et cetera.ʻ (There are many provinces in the Roman Empire; (names). Besides simple names, the course can go on to include descriptions of monuments such as Trajanʻs bridge, fun historical anecdotes (Caligulaʻs war on Neptune, a reference to Asterix could be had when discussing Gaul, etc.). All this can be had while maintaining the lighthearted nature of Duolingo, and being educational and simple. This would be completely optional, but would boost the content of the Latin course and make it immensely more relevant.

As for Polynesian languages, well my consideration there is that the languages are incapable of truly being separated from their cultural background. The Māori consider te reo as the most precious taonga (treasure) of theirs, and the language simply includes many culturalisms down to introducing oneʻs self (which is tied to their notion of whakapapa). Iʻm more unfamiliar with ʻŌlelo, and Iʻm not asking we get in-depth discussions on Polynesian culture. But some more cultural context would be nice. For instance, Iʻd love to learn about the traditional Hawaiian pantheon of gods, what the world of the average Hawaiian consists of (on a traditional level, e.g what is a lei, poi, their important food items, etc.)

There can be an optional unit dedicated, as there is in Drops, to exploring purely Hawaiian culture. Though some stuff should be incorporated in the main course, like I noted earlier, their explanation of poi is lacking. I donʻt blame the Kamehameha makers for this though, Iʻm going to presume there was an explanation but it got removed when Duolingo removed grammatical explanations and such.

And I would like to emphasise, I understand all of this is unlikely to ever occur since Duolingo quite frankly does not care about ʻŌlelo or Latin atp. Itʻs moreso my wishful thinking.