Some cheeses made in America --like Vermont cheddar-- are excellent. However, don't ever eat anything labled as "American" Cheese, especially not the sort that comes in individually-wrapped slices: it's a horrid, plastic, maybe-dairy-maybe-not quasi-food embraced by the equally awful fast food industry. "American" cheese is to cheese what Spam is to meat: it qualifies on a technicality, but that's about it.
I think, perhaps, that's the point. Since the Finnish course is still in beta, the structure is not optimal yet. However, something frustrating about EVERY duolingo course is that mobile users get screwed by not having access to the tips and notes for a section. I am hoping that the devs implement level by level notes followed by the pertinent exercises eventually.
Hmm, wiktionary tells me it's "an archaic locative singular form (with Proto-Uralic *-na) of the archaic/dialectal noun koto (“home”)".
So it's not from koti but from koto. The only "non-archaic/dialectal" use of the word koto I can come up with straight away is the compound word "lintukoto", which literally translates to a bird's home, but actually means a safe area with very little crime or anything else to fear. I guess there might be some other ones as well...
Interesting. Sounds like koti and kotona are siblings, both from the same root, rather than one being derived from the other. (And lintukoto a cousin --thank you for the vocabulary and context!) I had assumed kotono to be koti with a suffix tacked on, and was half expecting there to be an equivalent for any location, such as teatteri / teatterona, oopperatalo / oopperatalono, but that now appears unlikely.
Kotona ends with an -a all on its own; despite how it looks, that isn't a partitive ending. Were it to have a partitive suffix --which it wouldn't have, because it's neither noun nor adjective-- it would look like "kotonaa".
I can see how it might be a bit disorienting, though, seeing it in a partitive sentence before you're used to how partitive works.